Impregnated glass fiber strands and products including the same

ABSTRACT

The present invention provides an at least partially coated fiber strand comprising a plurality of glass fibers having a coating composition on at least a portion of at least one of the glass fibers, the coating composition comprising at least one coating comprising greater than 20 weight percent on a total solids basis of a plurality of particles selected from inorganic particles, organic hollow particles, composite particles, and mixtures of any of the foregoing, wherein the plurality of particles have a Mohs&#39; hardness value which does not exceed the Mohs&#39; hardness value of the glass fibers.

RELATED APPLICATIONS

This application is a continuing application of (a) U.S. patentapplication Ser. No. 09/620,523 of B. Novich et al. entitled “InorganicParticle-Coated Glass Fiber Strands and Products Including the Same”filed Jul. 20, 2000; (b) U.S. patent application Ser. No. 09/620,524 ofB. Novich et al. entitled “Inorganic Particle-Coated Glass Fiber Strandsand Products Including the Same” filed Jul. 20, 2000, now abandoned; (c)U.S. patent application Ser. No. 09/620,525 of B. Novich et al. entitled“Inorganic Particle-Coated Glass Fiber Strands and Products Includingthe Same” filed Jul. 20, 2000, now abandoned; and (d) U.S. patentapplication Ser. No. 09/620,526 of B. Novich et al. entitled “InorganicParticle-Coated Glass Fiber Strands and Products Including the Same”filed Jul. 20, 2000, now abandoned; which are continuing applications ofU.S. patent application Ser. No. 09/568,916 of Novich et al. entitled“Impregnated Glass Fiber Strands and Products Including the Same”, filedMay 11, 2000, now abandoned, which is a continuing application of U.S.patent application Ser. No. 09/548,379 of B. Novich et al. entitled“Impregnated Glass Fiber Strands and Products Including the Same”, filedApr. 12, 2000, now abandoned, which is a continuing application of U.S.patent application Ser. No. 09/527,034 of Novich et al. entitled“Impregnated Glass Fiber Strands and Products Including the Same”, filedMar. 16, 2000, now abandoned, which is (a) a continuation-in-part ofInternational Application PCT/US99/21443 of B. Novich et al. entitled“Glass Fiber-Reinforced Prepregs, Laminates, Electronic Circuit Boardsand Methods for Assembling Fabric”, with an international filing date ofOct. 8, 1999, which is a continuation-in-part of U.S. patent applicationSer. No. 09/170,578 of B. Novich et al. entitled “Glass Fiber-ReinforcedLaminates, Electronic Circuit Boards and Methods for Assembling aFabric”, filed Oct. 13, 1998, now abandoned, which is acontinuation-in-part of U.S. patent application Ser. No. 09/130,270 ofB. Novich et al. entitled “Glass Fiber-Reinforced Laminates, ElectronicCircuit Boards and Methods for Assembling a Fabric”, filed Aug. 6, 1998,now abandoned, which is a continuation-in-part application of U.S. Ser.No. 09/034,525 of B. Novich et al. entitled “Inorganic Lubricant-CoatedGlass Fiber Strands and Products Including the Same” filed Mar. 3, 1998,now abandoned; (b) also a continuation-in-part of U.S. patentapplication Ser. No. 09/170,780 of B. Novich et al. entitled “InorganicLubricant-Coated Glass Fiber Strands and Products Including the Same”filed Oct. 13, 1998, now abandoned, which is a continuation-in-partapplication of U.S. patent application Ser. No. 09/034,525 of B. Novichet al. entitled “Inorganic Lubricant-Coated Glass Fiber Strands andProducts Including the Same” filed Mar. 3, 1998, now abandoned; (c) alsoa continuation-in-part of U.S. patent application Ser. No. 09/170,781 ofB. Novich et al. entitled “Glass Fiber Strands Coated With ThermallyConductive Inorganic Solid Particles and Products Including the Same”filed Oct. 13, 1998, now abandoned, which is a continuation-in-partapplication of U.S. application Ser. No. 09/034,663 filed Mar. 3, 1998,now abandoned; (d) also a continuation-in-part of U.S. patentapplication Ser. No. 09/170,579 of B. Novich et al. entitled “Methodsfor Inhibiting Abrasive Wear of Glass Fiber Strands” filed Oct. 13,1998, now abandoned, which is a continuation-in-part application of U.S.patent application Ser. No. 09/034,078 filed Mar. 3, 1998, nowabandoned; (e) also a continuation-in-part of International ApplicationPCT/US99/21442 to B. Novich et al. entitled “Impregnated Glass FiberStrands and Products Including the Same”, with an international filingdate of Oct. 8, 1999, which a continuation-in-part of U.S. patentapplication Ser. No. 09/170,566 of B. Novich et al. entitled“Impregnated Glass Fiber Strands and Products Including the Same” filedOct. 13, 1998, now abandoned, which is a continuation-in-partapplication of U.S. patent application Ser. No. 09/034,077 filed Mar. 3,1998, now abandoned; and (f) also a continuation-in-part of U.S. patentapplication Ser. No. 09/170,565 of B. Novich et al. entitled “InorganicParticle-Coated Glass Fiber Strands and Products Including the Same”filed Oct. 13, 1998, now abandoned, which is a continuation-in-partapplication of U.S. patent application Ser. No. 09/034,056 filed Mar. 3,1998, now abandoned.

This application 09/020,523 filed Jul. 20, 2000 claims the benefit ofU.S. Provisional Application Nos. 60/133,075 filed May 7, 1999;60/133,076 filed May 7, 1999; 60/136,110 filed May 26, 1999; 60/146,337filed Jul. 30, 1999; 60/146,605 filed Jul. 30, 1999; 60/146862 filedAug. 3, 1999; and 60/183,562 filed Feb. 18, 2000.

This invention relates generally to coated fiber strands for reinforcingcomposites and, more specifically, to coated fiber strands that arecompatible with a matrix material that the strands are incorporatedinto.

In thermosetting molding operations, good wet-through (penetration of apolymeric matrix material through the mat or fabric) and “wet-through”(penetration of a polymeric matrix material through the individualbundles or strands of fibers in the mat or fabric) properties aredesirable. In contrast, good dispersion properties (i.e., gooddistribution properties of fibers within a thermoplastic material) areof predominant concern in typical thermoplastic molding operations.

In the case of composites or laminates formed from fiber strands woveninto fabrics, in addition to providing good wet-through and good wet-outproperties of the strands, it is desirable that the coating on thesurfaces of the fibers strands protect the fibers from abrasion duringprocessing, provide for good weavability, particularly on air-jet loomsand be compatible with the polymeric matrix material into which thefiber strands are incorporated. However, many sizing components are notcompatible with the polymeric matrix materials and can adversely affectadhesion between the glass fibers and the polymeric matrix material. Forexample, starch, which is a commonly used sizing component for textilefibers, is generally not compatible with polymeric matrix material. As aresult, these incompatible materials must be removed from the fabricprior to impregnation with the polymeric matrix material.

The removal of such non-resin compatible sizing materials, i.e.,de-greasing or de-oiling the fabric, can be accomplished through avariety of techniques. The removal of these non-resin compatible sizingmaterials is most commonly accomplished by exposing the woven fabric toelevated temperatures for extended periods of time to thermallydecompose the sizing(s) (commonly referred to as heat-cleaning). Aconventional heat-cleaning process involves heating the fabric at 380°C. for 60-80 hours. However, such heat cleaning steps are detrimental tothe strength of the glass fibers, are not always completely successfulin removing the incompatible materials and can further contaminate thefabric with sizing decomposition products. Other methods of removingsizing materials have been tried, such as water washing and/or chemicalremoval. However, such methods generally require significantreformulation of the sizing compositions for compatibility with suchwater washing and/or chemical removal operations and are generally notas effective as heat-cleaning in removing all the incompatible sizingmaterials.

In addition, since the weaving process can be quite abrasive to thefiber glass yarns, those yarns used as warp yarns are typicallysubjected to a secondary coating step prior to weaving, commonlyreferred to as “slashing”, to coat the warp yarns with an abrasionresistance coating (commonly referred to as a “slashing size”) to helpminimize abrasive wear of the glass fibers. The slashing size isgenerally applied over the primary size that was previously applied tothe glass fibers during the fiber forming operation. However, sincetypical slashing sizes are also not generally compatible with thepolymeric matrix materials, they too must be removed from the wovenfabric prior to its incorporation into the resin.

Furthermore, to improve adhesion between the decreased or de-oiledfabric and the polymeric resin, a finishing size, typically a silanecoupling agent and water, is applied to the fabric to re-coat the glassfibers in yet another processing step (commonly called “finishing”).

All of these non-value added processing steps: slashing, decreasing orde-oiling, and finishing, increase fabric production cycle time andcost. Additionally, they generally require significant investment incapital equipment and labor. Moreover, the added handling of the fabricassociated with these processing steps can lead to fabric damage anddecreased quality.

Efforts have been directed toward improving the efficiency oreffectiveness of some of these processing steps. There neverthelessremains a need for coatings that can accomplish one or more of thefollowing: inhibit abrasion and breakage of glass fibers; be compatiblewith a wide variety of matrix materials; and provide for good wet-outand wet-through by the matrix material. In addition, it would beparticularly advantageous if the coatings were compatible with modernair-jet weaving equipment to increase productivity. Furthermore, itwould be advantageous to eliminate the non-value added processing stepsin a fabric forming operation while maintaining the fabric qualityrequired for electronic support applications and providing for goodlaminate properties.

The foregoing summary, as well as the following detailed description ofthe preferred embodiments, will be better understood when read inconjunction with the appended drawings. In the drawings:

FIG. 1 is a perspective view of a coated fiber strand at least partiallycoated with a coating composition according to the present invention;

FIG. 2 is a perspective view of a coated fiber strand at least partiallycoated with a sizing composition and a secondary coating compositionaccording to the present invention on at least a portion of the sizingcomposition;

FIG. 3 is a perspective view of a coated fiber strand at least partiallycoated with a sizing composition, a secondary coating composition on atleast a portion of the sizing composition, and a tertiary coatingcomposition according to the present invention on at least a portion ofthe secondary coating composition;

FIG. 4 is a top plan view of a composite product according to thepresent invention;

FIG. 5 is a top plan view of a fabric according to the presentinvention;

FIG. 6 is a schematic diagram of a method for assembling a fabric andforming a laminate according to the present invention;

FIG. 7 is a cross-sectional view of an electronic support according tothe present invention;

FIGS. 8 and 9 are cross-sectional views of alternate embodiments of anelectronic support according to the present invention;

FIG. 10 is a schematic diagram of a method for forming an aperture in alayer of fabric of an electronic support;

FIG. 11 is an end view of a drill illustrating the primary cutting edge;

FIG. 12 is a schematic of a drill hole pattern; and

FIG. 13 is a diagram of circuit patterns.

The fiber strands of the present invention have a unique coating thatnot only preferably inhibits abrasion and breakage of the fibers duringprocessing but also provides at least one of the following properties:good wet-through, wet-out and dispersion properties in formation ofcomposites. As fully defined below, a “strand” comprises a plurality ofindividual fibers, i.e., at least two fibers. As used herein,“composite” means the combination of the coated fiber strand of thepresent invention with an additional material, for example, but notlimited to, one or more layers of a fabric incorporating the coatedfiber strand combined with a polymeric matrix material to form alaminate. Good laminate strength, good thermal stability, goodhydrolytic stability (i.e. resistance to migration of water along thefiber/polymeric matrix material interface), low corrosion and reactivityin the presence of high humidity, reactive acids and alkalies andcompatibility with a variety of polymeric matrix materials, which caneliminate the need for removing the coating, and in particular heat orpressurized water cleaning, prior to lamination, are other desirablecharacteristics which can be exhibited by the coated fiber strands ofthe present invention.

Preferably, the coated fiber strands of the present invention providegood processability in weaving and knitting. Low fuzz and halos, lowbroken filaments, low strand tension, high Liability and low insertiontime are preferred characteristics, individually or in combination,provided by the coated glass fiber strands of the present invention thatpreferably facilitate weaving and knitting and consistently provide afabric with few surface defects for printed circuit board applications.In addition, coated fiber strands of the present invention can besuitable for use in an air jet weaving process. As used herein, “air jetweaving” means a type of fabric weaving in which the fill yarn (weft) isinserted into the warp shed by a blast of compressed air from one ormore air jet nozzles.

The coated fiber strands of the present invention preferably have aunique coating that can facilitate thermal conduction along coatedsurfaces of the fibers. When used as a continuous reinforcement for anelectronic circuit board, such coated glass fibers of the presentinvention can provide a mechanism to promote heat dissipation from aheat source (such as a chip or circuit) along the reinforcement toconduct heat away from the electronic components and thereby inhibitthermal degradation and/or deterioration of the circuit components,glass fibers and polymeric matrix material. The coated glass fibers ofthe present invention preferably provide a higher thermal conductivityphase than the matrix material, i.e., a preferential path for heatdissipation and distribution, thereby reducing differential thermalexpansion and warpage of the electronic circuit board and improvingsolder joint reliability.

The coated glass fiber strands of the present invention preferablylessen or eliminate the need for incorporating thermally conductivematerials in the matrix resin, which improves laminate manufacturingoperations and lowers costly matrix material supply tank purging andmaintenance.

The coated fiber strands of the present invention preferably possesshigh strand openness. As used herein, the term “high strand openness”means that the strand has an enlarged cross-sectional area and that thefilaments of the strand are not tightly bound to one another. The highstrand openness can facilitate penetration or wet out of matrixmaterials into the strand bundles.

Composites, and in particular laminates, of the present invention, madefrom the fiber strands of the present invention, preferably possess atleast one of the following properties: low coefficient of thermalexpansion; good flexural strength; good interlaminar bond strength; andgood hydrolytic stability, i.e., the resistance to migration of wateralong the fiber/matrix interface. Additionally, electronic supports andprinted circuit boards of the present invention made from the fiberstrands in accordance with the present invention preferably have atleast one of the following properties: good drillability; and resistanceto metal migration (also referred to as cathodic-anodic filamentformation or CAF). See Tummala (Ed.) et al., Microelectronics PackagingHandbook, (1989) at pages 896-897 and IPC-TR476B, “ElectrochemicalMigration: Electrochemically Induced Failures in Printed Wiring Boardsand Assemblies”, (1997) which are specifically incorporated by referenceherein. Fiber strands in accordance with the present invention with gooddrillability have at least one of low tool wear during drilling and goodlocational accuracy of drilled holes.

As described above, typical fabric forming operations involve subjectingfiber glass yarns and fabric made therefrom to several non-value addedprocessing steps, such as slashing, heat-cleaning and finishing. Thepresent invention preferably provides methods of forming fabrics,laminates, electronic supports and printed circuit boards that eliminatenon-value added processing steps from the fabric forming process whileproviding fabrics having quality suitable for use in electronicpackaging applications. Other advantages of preferred embodiments of thepresent invention include reduced production cycle time, elimination ofcapital equipment, reduced fabric handling and labor costs, good fabricquality and good final product properties.

The present invention also provides methods to inhibit abrasive wear offiber strands from contact with other solid objects, such as portions ofa winding, weaving or knitting device, or by interfilament abrasion byselecting fiber strands having a unique coating of the presentinvention.

For the purposes of this specification, other than in the operatingexamples, or where otherwise indicated, all numbers expressingquantities of ingredients, reaction conditions, and so forth used in thespecification and claims are to be understood as being modified in allinstances by the term “about.” Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the followingspecification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Referring now to FIG. 1, wherein like numerals indicate like elementsthroughout, there is shown in FIG. 1 a coated fiber strand 10 comprisinga plurality of fibers 12, according to the present invention. As usedherein, “strand” means a plurality of individual fibers, i.e., at leasttwo fibers, and the strand can comprise fibers made of differentfiberizable materials. (The bundle of fibers can also be referred to as“yarn”.) The term “fiber” means an individual filament. Although notlimiting the present invention, the fibers 12 preferably have an averagenominal fiber diameter ranging from 3 to 35 micrometers. Preferably, theaverage nominal fiber diameter of the present invention is 5 micrometersand greater. For “fine yarn” applications, the average nominal fiberdiameter preferably ranges from 5 to 7 micrometers.

The fibers 12 can be formed from any type of fiberizable material knownto those skilled in the art including fiberizable inorganic materials,fiberizable organic materials and mixtures of any of the foregoing. Theinorganic and organic materials can be either man-made or naturallyoccurring materials. One skilled in the art will appreciate that thefiberizable inorganic and organic materials can also be polymericmaterials. As used herein, the term “polymeric material” means amaterial formed from macromolecules composed of long chains of atomsthat are linked together and that can become entangled in solution or inthe solid state¹. As used herein, the term “fiberizable” means amaterial capable of being formed into a generally continuous filament,fiber, strand or yarn.

¹ James Mark et al. Inorganic Polymers, Prentice Hall Polymer Scienceand Engineering Series, (1992) at page 1 which is hereby incorporated byreference.

Preferably, the fibers 12 are formed from an inorganic, fiberizableglass material. Fiberizable glass materials useful in the presentinvention include but are not limited to those prepared from fiberizableglass compositions such as “E-glass”, “A-glass”, “C-glass”, “D-glass”,“R-glass”, “S-glass”, and E-glass derivatives. As used herein, “E-glassderivatives” means glass compositions that include minor amounts offluorine and/or boron and most preferably are fluorine-free and/orboron-free. Furthermore, as used herein, “minor amounts of fluorine”means less than 0.5 weight percent fluorine, preferably less than 0.1weight percent fluorine, and “minor amounts of boron” means less than 5weight percent boron, preferably less than 2 weight percent boron.Basalt and mineral wool are examples of other fiberizable glassmaterials useful in the present invention. Preferred glass fibers areformed from E-glass or E-glass derivatives. Such compositions are wellknown to those skilled in the art and further discussion thereof is notbelieved to be necessary in view of the present disclosure.

The glass fibers of the present invention can be formed in any suitablemethod known in the art, for forming glass fibers. For example, glassfibers can be formed in a direct-melt fiber forming operation or in anindirect, or marble-melt, fiber forming operation. In a direct-meltfiber forming operation, raw materials are combined, melted andhomogenized in a glass melting furnace. The molten glass moves from thefurnace to a forehearth and into fiber forming apparatuses where themolten glass is attenuated into continuous glass fibers. In amarble-melt glass forming operation, pieces or marbles of glass havingthe final desired glass composition are preformed and fed into a bushingwhere they are melted and attenuated into continuous glass fibers. If apremelter is used, the marbles are fed first into the premelter, melted,and then the melted glass is fed into a fiber forming apparatus wherethe glass is attenuated to form continuous fibers. In the presentinvention, the glass fibers are preferably formed by the direct-meltfiber forming operation. For additional information relating to glasscompositions and methods of forming the glass fibers, see K.Loewenstein, The Manufacturing Technology of Continuous Glass Fibres,(3d Ed. 1993) at pages 30-44, 47-103, and 115-165; U.S. Pat. Nos.4,542,106 and 5,789,329; and IPC-EG-140 “Specification for FinishedFabric Woven from ‘E’ Glass for Printed Boards” at page 1, a publicationof The Institute for Interconnecting and Packaging Electronic Circuits(June 1997), which are specifically incorporated by reference herein.

Non-limiting examples of suitable non-glass fiberizable inorganicmaterials include ceramic materials such as silicon carbide, carbon,graphite, mullite, aluminum oxide and piezoelectric ceramic materials.Non-limiting examples of suitable fiberizable organic materials includecotton, cellulose, natural rubber, flax, ramie, hemp, sisal and wool.Non-limiting examples of suitable fiberizable organic polymericmaterials include those formed from polyamides (such as nylon andaramids), thermoplastic polyesters (such as polyethylene terephthalateand polybutylene terephthalate), acrylics (such as polyacrylonitriles),polyolefins, polyurethanes and vinyl polymers (such as polyvinylalcohol). Non-glass fiberizable materials useful in the presentinvention and methods for preparing and processing such fibers arediscussed at length in the Encyclopedia of Polymer Science andTechnology, Vol. 6 (1967) at pages 505-712, which is specificallyincorporated by reference herein.

It is understood that blends or copolymers of any of the above materialsand combinations of fibers formed from any of the above materials can beused in the present invention, if desired. Moreover, the term strandencompasses at least two different fibers made from differingfiberizable materials. In a preferred embodiment, the fiber strands ofthe present invention contain at least one glass fiber, although theymay contain other types of fibers.

The present invention will now be discussed generally in the context ofglass fiber strands, although one skilled in the art would understandthat the strand 10 can comprise fibers 12 formed from any fiberizablematerial known in the art as discussed above. Thus, the discussion thatfollows in terms of glass fibers applies generally to the other fibersdiscussed above.

With continued reference to FIG. 1, in a preferred embodiment, at leastone and preferably all of the fibers 12 of fiber strand 10 of thepresent invention have a layer 14 of a coating composition, preferably aresidue of a coating composition, on at least a portion 17 of thesurfaces 16 of the fibers 12 to protect the fiber surfaces 16 fromabrasion during processing and inhibit fiber breakage. Preferably, thelayer 14 is present on the entire outer surface 16 or periphery of thefibers 12.

The coating compositions of the present invention are preferably aqueouscoating compositions and more preferably aqueous, resin compatiblecoating compositions. Although not preferred for safety reasons, thecoating compositions can contain volatile organic solvents such asalcohol or acetone as needed, but preferably are free of such solvents.Additionally, the coating compositions of the present invention can beused as primary sizing compositions and/or secondary sizing or coatingcompositions.

As used herein, in a preferred embodiment the terms “size”, “sized” or“sizing” refers to any coating composition applied to the fibers. Theterms “primary size” or “primary sizing” refer to a coating compositionapplied to the fibers immediately after formation of the fibers. Theterms “secondary size”, “secondary sizing” or “secondary coating” meancoating compositions applied to the fibers after the application of aprimary size. The terms “tertiary size”. “tertiary sizing” or “tertiarycoating” mean coating compositions applied to the fibers after theapplication of a secondary size. These coatings can be applied to thefiber before the fiber is incorporated into a fabric or it can beapplied to the fiber after the fiber is incorporated into a fabric, e.g.by coating the fabric. In an alternative embodiment, the terms “size”,“sized” and “sizing” additionally refer to a coating composition (alsoknown as a “finishing size”) applied to the fibers after at least aportion, and preferably all of a conventional, non-resin compatiblesizing composition has been removed by heat or chemical treatment, i.e.,the finishing size is applied to bare glass fibers incorporated into afabric form.

As used herein, the term “resin compatible” means the coatingcomposition applied to the glass fibers is compatible with the matrixmaterial into which the glass fibers will be incorporated such that thecoating composition (or selected coating components) achieves at leastone of the following properties: does not require removal prior toincorporation into the matrix material (such as by de-greasing orde-oiling), facilitates good wet-out and wet-through of the matrixmaterial during conventional processing and results in final compositeproducts having desired physical properties and hydrolytic stability.

The coating composition of the present invention comprises one or more,and preferably a plurality of particles 18 that when applied to at leastone fiber 23 of the plurality of fibers 12 adhere to the outer surface16 of the at least one fiber 23 and provide one or more interstitialspaces 21 between adjacent glass fibers 23, 25 of the strand 10 as shownin FIG. 1. These interstitial spaces 21 correspond generally to the size19 of the particles 18 positioned between the adjacent fibers.

The particles 18 of the present invention are preferably discreteparticles. As used herein, the term “discrete” means that the particlesdo not tend to coalesce or combine to form continuous films underconventional processing conditions, but instead substantially retaintheir individual distinctness, and generally retain their individualshape or form. The discrete particles of the present invention mayundergo shearing, i.e., the removal of a layer or sheet of atoms in aparticle, necking, i.e., a second order phase transition between atleast two particles, and partial coalescence during conventional fiberprocessing, and still be considered to be “discrete” particles.

The particles 18 of the present invention are preferably dimensionallystable. As used herein, the term “dimensionally stable particles” meansthat the particles will generally maintain their average particle sizeand shape under conventional fiber processing conditions, such as theforces generated between adjacent fibers during weaving, roving andother processing operations, so as to maintain the desired interstitialspaces 21 between adjacent fibers 23, 25. In other words, dimensionallystable particles preferably will not crumble, dissolve or substantiallydeform in the coating composition to form a particle having a maximumdimension less than its selected average particle size under typicalglass fiber processing conditions, such as exposure to temperatures ofup to 25° C., preferably up to 100° C., and more preferably up to 140°C. Additionally, the particles 18 should not substantially enlarge orexpand in size under glass fiber processing conditions and, moreparticularly, under composite processing conditions where the processingtemperatures can exceed 150° C. As used herein, the phrase “should notsubstantially enlarge in size” in reference to the particles means thatthe particles should not expand or increase in size to more thanapproximately three times their initial size during processing.Furthermore, as used herein, the term “dimensionally stable particles”covers both crystalline and non-crystalline particles.

Preferably, the coating compositions of the present invention aresubstantially free of heat expandable particles. As used herein, theterm “heat expandable particles” means particles filled with orcontaining a material, which, when exposed to temperatures sufficient tovolatilize the material, expand or substantially enlarge in size. Theseheat expandable particles therefore expand due to a phase change of thematerial in the particles, e.g., a blowing agent, under normalprocessing conditions. Consequently, the term “non-heat expandableparticle” refers to a particle that does not expand due a phase changeof the material in the particle under normal fiber processingconditions, and, in one embodiment of the present invention, the coatingcompositions comprise at least one non-heat expandable particle.

Generally, the heat expandable particles are hollow particles with acentral cavity. In a non-limiting embodiment of the present invention,the cavity can be at least partial filled with a non-solid material suchas a gas, liquid, and/or a gel.

As used herein, the term “substantially free of heat expandableparticles” means less than 50 weight percent of heat expandableparticles on a total solids basis, more preferably less than 35 weightpercent. More preferably, the coating compositions of the presentinvention are essentially free of heat expandable particles. As usedherein, the term “essentially free of heat expandable particles” meansthe sizing composition comprises less than 20 weight percent of heatexpandable particles on a total solids basis, more preferably less than5 weight percent, and most preferably less than 0.001 weight percent.

The particles 18 are preferably non-waxy. The term “non-waxy” means thematerials from which the particles are formed are not wax-like. As usedherein, the term “wax-like” means materials composed primarily ofunentangled hydrocarbons chains having an average carbon chain lengthranging from 25 to 100 carbon atoms²³.

² L. H. Sperling Introduction of Physical Polymer Science, John Wileyand Sons, Inc. (1986) at pages 2-5, which are specifically incorporatedby reference herein.

³ W. Pushaw, et al. “Use of Micronised Waxes and Wax Dispersions inWaterborne Systems” Polymers, Paint, Colours Journal, V.189, No. 4412January 1999 at pages 18-21 which are specifically incorporated byreference herein.

In one preferred embodiment of the present invention, the particles 18in the present invention are discrete, dimensionally stable, non-waxyparticles.

The particles 18 can have any shape or configuration desired. Althoughnot limiting in the present invention, examples of suitable particleshapes include spherical (such as beads, microbeads or hollow spheres),cubic, platy or acicular (elongated or fibrous). Additionally, theparticles 18 can have an internal structure that is hollow, porous orvoid free, or a combination thereof, e.g. a hollow center with porous orsolid walls. For more information on suitable particle characteristicssee H. Katz et al. (Ed.), Handbook of Fillers and Plastics (1987) atpages 9-10, which are specifically incorporated by reference herein.

The particles 18 can be formed from materials selected from polymericand non-polymeric inorganic materials, polymeric and non-polymericorganic materials, composite materials, and mixtures of any of theforegoing. As used herein, the term “polymeric inorganic material” meansa polymeric material having a backbone repeat unit based on an elementor elements other than carbon. For more information see J. E. Mark etal. at page 5, which is specifically incorporated by reference herein.As used herein, the term “polymeric organic materials” means syntheticpolymeric materials, semisynthetic polymeric materials and naturalpolymeric materials having a backbone repeat unit based on carbon.

An “organic material”, as used herein, means carbon containing compoundswherein the carbon is typically bonded to itself and to hydrogen, andoften to other elements as well, and excludes binary compounds such asthe carbon oxides, the carbides, carbon disulfide, etc.; such ternarycompounds as the metallic cyanides, metallic carbonyls, phosgene,carbonyl sulfide, etc.; and carbon-containing ionic compounds such asthe metallic carbonates, such as calcium carbonate and sodium carbonate.See R. Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed.1993) at pages 761-762, and M. Silberberg, Chemistry The MolecularNature of Matter and Change (1996) at page 586, which are specificallyincorporated by reference herein.

As used herein, the term “inorganic materials” means any material thatis not an organic material.

As used herein, the term “composite material” means a combination of twoor more differing materials. The particles formed from compositematerials generally have a hardness at their surface that is differentfrom the hardness of the internal portions of the particle beneath itssurface. More specifically, the surface of the particle can be modifiedin any manner well known in the art, including, but not limited to,chemically or physically changing its surface characteristics usingtechniques known in the art, such that the surface hardness of theparticle is equal to or less than the hardness of the glass fibers whilethe hardness of the particle beneath the surface is greater than thehardness of the glass fibers. For example, a particle can be formed froma primary material that is coated, clad or encapsulated with one or moresecondary materials to form a composite particle that has a softersurface. In yet another alternative embodiment, particles formed fromcomposite materials can be formed from a primary material that iscoated, clad or encapsulated with a different form of the primarymaterial. For more information on particles useful in the presentinvention, see G. Wypych, Handbook of Fillers, 2nd Ed. (1999) at pages15-202, which are specifically incorporated by reference herein.

Representative non-polymeric, inorganic materials useful in forming theparticles 18 of the present invention include inorganic materialsselected from graphite, metals, oxides, carbides, nitrides, borides,sulfides, silicates, carbonates, sulfates and hydroxides. A non-limitingexample of a suitable inorganic nitride from which the particles 18 areformed is boron nitride, a preferred embodiment of the presentinvention. Boron nitride particles having a hexagonal crystal structureare particularly preferred. A non-limiting example of a useful inorganicoxide is zinc oxide. Suitable inorganic sulfides include molybdenumdisulfide, tantalum disulfide, tungsten disulfide and zinc sulfide.Useful inorganic silicates include aluminum silicates and magnesiumsilicates, such as vermiculite. Suitable metals include molybdenum,platinum, palladium, nickel, aluminum, copper, gold, iron, silver,alloys, and mixtures of any of the foregoing.

In one non-limiting embodiment of the invention, the particles 18 areformed from solid lubricant materials. As used herein, the term “solidlubricant” means any solid used between two surfaces to provideprotection from damage during relative movement and/or to reducefriction and wear. In one embodiment, the solid lubricants are inorganicsolid lubricants. As used herein, “inorganic solid lubricant” means thatthe solid lubricants have a characteristic crystalline habit whichcauses them to shear into thin, flat plates which readily slide over oneanother and thus produce an antifriction lubricating effect between thefiber surfaces, preferably the glass fiber surface, and an adjacentsolid surface, at least one of which is in motion. See R. Lewis, Sr.,Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at page 712,which is specifically incorporated by reference herein. Friction is theresistance to sliding one solid over another. F. Clauss, SolidLubricants and Self-Lubricating Solids (1972) at page 1, which isspecifically incorporated by reference herein.

In one non-limiting embodiment of the invention, the particles 18 have alamellar structure. Particles having a lamellar structure are composedof sheets or plates of atoms in hexagonal array, with strong bondingwithin the sheet and weak van der Waals bonding between sheets,providing low shear strength between sheets. A non-limiting example of alamellar structure is a hexagonal crystal structure. K. Ludema,Friction, Wear, Lubrication (1996) at page 125, Solid Lubricants andSelf-Lubricating Solids at pages 19-22, 42-54, 75-77, 80-81, 82, 90-102,113-120 and 128; and W. Campbell, “Solid Lubricants”, BoundaryLubrication; An Appraisal of World Literature, ASME Research Committeeon Lubrication (1969) at pages 202-203, which are specificallyincorporated by reference herein. Inorganic solid particles having alamellar fullerene (buckyball) structure are also useful in the presentinvention.

Non-limiting examples of suitable materials having a lamellar structurethat are useful in forming the particles 18 of the present inventioninclude boron nitride, graphite, metal dichalcogenides, mica, talc,gypsum, kaolinite, calcite, cadmium iodide, silver sulfide, and mixturesof any of the foregoing. Preferred materials include boron nitride,graphite, metal dichalcogenides, and mixtures of any of the foregoing.Suitable metal dichalcogenides include molybdenum disulfide, molybdenumdiselenide, tantalum disulfide, tantalum diselenide, tungsten disulfide,tungsten diselenide, and mixtures of any of the foregoing.

In one embodiment, the particles 18 are formed from an inorganic solidlubricant material having a lamellar structure. A non-limiting exampleof an inorganic solid lubricant material having a lamellar structure foruse in the coating composition of the present invention is boronnitride, preferably boron nitride having a hexagonal crystal structure.Particles formed from boron nitride, zinc sulfide and montmorillonitealso provide good whiteness in composites with polymeric matrixmaterials such as nylon 6,6.

Non-limiting examples of particles formed from boron nitride that aresuitable for use in the present invention are POLARTHERM® 100 Series (PT120, PT 140, PT 160 and PT 180); 300 Series (PT 350) and 600 Series (PT620, PT 630, PT 640 and PT 670) boron nitride powder particles,commercially available from Advanced Ceramics Corporation of Lakewood,Ohio. “PolarTherm® Thermally Conductive Fillers for PolymericMaterials”, a technical bulletin of Advanced Ceramics Corporation ofLakewood, Ohio (1996), which is specifically incorporated by referenceherein. These particles have a thermal conductivity of 250300 Watts permeter °K at 25° C., a dielectric constant of 3.9 and a volumeresistivity of 10¹⁵ ohm-centimeters. The 100 Series powder particleshave an average particle size ranging from 5 to 14 micrometers, the 300Series powder particles have an average particle size ranging from 100to 150 micrometers and the 600 Series powder particles have an averageparticle size ranging from 16 to greater than 200 micrometers. Inparticular, as reported by its supplier, POLARTHERM 160 particles havean average particle size of 6 to 12 micrometers, a particle size rangeof submicrometer to 70 micrometers, and a particle size distribution asfollows:

% > 10 50 90 Size (μm) 18.4 7.4 0.6According to this distribution, ten percent of the POLARTHERM® 160 boronnitride particles that were measured had an average particle sizegreater than 18.4 micrometers. As used herein, the “average particlesize” refers to the mean particle size of the particles.

The average particle size of the particles according to the presentinvention can be measured according to known laser scatteringtechniques. In one non-limiting embodiment of the present invention, theparticles size is measured using a Beckman Coulter LS 230 laserdiffraction particle size instrument, which uses a laser beam with awave length of 750 nm to measure the size of the particles and assumesthe particle has a spherical shape, i.e., the “particle size” refers tothe smallest sphere that will completely enclose the particle. Forexample, particles of POLARTHERM® 160 boron nitride particles measuredusing the Beckman Coulter LS 230 particle size analyzer were found tohave an average particle size was 11.9 micrometers with particlesranging from submicrometer to 35 micrometers and having the followingdistribution of particles:

% > 10 50 90 Size (μm) 20.6 11.3 4.0According to this distribution, ten percent of the POLARTHERM® 160 boronnitride particles that were measured had an average particle sizegreater than 20.6 micrometers.

In another non-limiting embodiment of the present invention, theparticles 18 are formed from inorganic materials that arenon-hydratable. As used herein, “non-hydratable” means that theinorganic particles do not react with molecules of water to formhydrates and do not contain water of hydration or water ofcrystallization. A “hydrate” is produced by the reaction of molecules ofwater with a substance in which the H—OH bond is not split. See R.Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) atpages 609-610 and T. Pyrros, Chemistry, (1967) at pages 186-187, whichare specifically incorporated by reference herein. In the formulas ofhydrates, the addition of the water molecules is conventionallyindicated by a centered dot, e.g., 3MgO·4SiO₂·H₂O (talc),Al₂O₃·2SiO₂·2H₂O (kaolinite). Structurally, hydratable inorganicmaterials include at least one hydroxyl group within a layer of acrystal lattice (but not including hydroxyl groups in the surface planesof a unit structure or materials which absorb water on their surfaceplanes or by capillary action), for example as shown in the structure ofkaolinite given in FIG. 3.8 at page 34 of J. Mitchell, Fundamentals ofSoil Behavior (1976) and as shown in the structure of 1:1 and 2:1 layerminerals shown in FIGS. 18 and 19, respectively, of H. van Olphen, ClayColloid Chemistry, (2d Ed. 1977) at page 62, which are specificallyincorporated by reference herein. A “layer” of a crystal lattice is acombination of sheets, which is a combination of planes of atoms. (SeeMinerals in Soil Environments, Soil Science Society of America (1977) atpages 196-199, which is specifically incorporated by reference herein).The assemblage of a layer and interlayer material (such as cations) isreferred to as a unit structure.

Hydrates contain coordinated water, which coordinates the cations in thehydrated material and cannot be removed without the breakdown of thestructure, and/or structural water, which occupies interstices in thestructure to add to the electrostatic energy without upsetting thebalance of charge. R. Evans, An Introduction to Crystal Chemistry (1948)at page 276, which is specifically incorporated by reference herein.Generally, the coating compositions contain no more than 50 weightpercent hydratable particles. In one non-limiting embodiment of thepresent invention, the coating composition is preferably essentiallyfree of hydratable particles. As used herein, the term “essentially freeof hydratable particles” means the coating composition comprises lessthan 20 weight percent of hydratable particles on a total solids basis,more preferably less than 5 weight percent, and most preferably lessthan 0.001 weight percent. In one embodiment of the present invention,the particles 18 are formed from a non-hydratable, inorganic solidlubricant material.

The coating compositions according to the present invention can containparticles formed from hydratable or hydrated inorganic materials in lieuof or in addition to the non-hydratable inorganic materials discussedabove. Non-limiting examples of such hydratable inorganic materials areclay mineral phyllosilicates, including micas (such as muscovite), talc,montmorillonite, kaolinite and gypsum. As explained above, particlesformed from such hydratable or hydrated materials generally constituteno more than 50 weight percent of the particles in the coatingcomposition.

In another embodiment of the present invention, the particles 18 can beformed from non-polymeric, organic materials. Examples of non-polymeric,organic materials useful in the present invention include but are notlimited to stearates (such as zinc stearate and aluminum stearate),carbon black and stearamide.

In yet another embodiment of the present invention, the particles 18 canbe formed from inorganic polymeric materials. Non-limiting examples ofuseful inorganic polymeric materials include polyphosphazenes,polysilanes, polysiloxane, polygeremanes, polymeric sulfur, polymericselenium, silicones, and mixtures of any of the foregoing. A specificnon-limiting example of a particle formed from an inorganic polymericmaterial suitable for use in the present invention is TOSPEARL⁴, whichis a particle formed from cross-linked siloxanes and Is commerciallyavailable from Toshiba Silicones Company, Ltd. of Japan.

⁴ See R. J. Perry “Applications for Cross-Linked Siloxane Particles”Chemtech. February 1999 at pages 39-44.

In still another embodiment of the present invention, the particles 18can be formed from synthetic, organic polymeric materials. Suitableorganic polymeric materials include, but are not limited to,thermosetting materials and thermoplastic materials. Suitablethermosetting materials include thermosetting polyesters, vinyl esters,epoxy materials, phenolics, aminoplasts, thermosetting polyurethanes,and mixtures of any of the foregoing. A specific, non-limiting exampleof a preferred synthetic polymeric particle formed from an epoxymaterial is an epoxy microgel particle.

Suitable thermoplastic materials include thermoplastic polyesters,polycarbonates, polyolefins, acrylic polymers, polyamides, thermoplasticpolyurethanes, vinyl polymers, and mixtures of any of the foregoing.Preferred thermoplastic polyesters include, but are not limited to,polyethylene terephthalate, polybutylene terephthalate and polyethylenenaphthalate. Preferred polyolefins include, but are not limited to,polyethylene, polypropylene and polyisobutene. Preferred acrylicpolymers include copolymers of styrene and an acrylic acid monomer andpolymers containing methacrylate. Non-limiting examples of syntheticpolymeric particles formed from an acrylic copolymer are RHOPLEX® B-85⁵,which is an opaque, non-crosslinking solid acrylic particle emulsion,ROPAQUE® HP-1055⁶, which is an opaque, non-film-forming, styrene acrylicpolymeric synthetic pigment having a 1.0 micrometer particle size, asolids content of 26.5 percent by weight and a 55 percent void volume,ROPAQUE® OP-96⁷ and ROPAQUE® HP-543P⁸, which are identical, each beingan opaque, non-film-forming, styrene acrylic polymeric synthetic pigmentdispersion having a particle size of 0.55 micrometers and a solidscontent of 30.5 percent by weight, and ROPAQUE® OP-62 LO⁹ which is alsoan opaque, non-film-forming, styrene acrylic polymeric synthetic pigmentdispersion having a particles size of 0.40 micrometers and a solidscontent of 36.5 percent by weight. Each of these specific particles iscommercially available from Rohm and Haas Company of Philadelphia, Pa.

⁵ See “Chemicals for the Textile Industry” September 1987, availablefrom Rohm and Haas Company, Philadelphia, Pa.

⁶ See product property sheet entitled: “ROPAQUE® HP-1055, Hollow SpherePigment for Paper and Paperboard Coatings” October 1994, available fromRohm and Haas Company, Philadelphia, Pa. at page 1, which is herebyincorporated by reference.

⁷ See product technical bulletin entitled: “ArchitecturalCoatings-ROPAQUE® OP-96, The All Purpose Pigment”, April 1997 availablefrom Rohm and Haas Company, Philadelphia, Pa. at page 1 which is herebyincorporated by reference.

⁸ ROPAQUE® HP-543P and ROPAQUE® OP-96 are the same material; thematerial is identified as ROPAQUE® HP-543P in the paint industry and asROPAQUE® OP-96 in the coatings industry.

⁹ See product technical bulletin entitled: “ArchitecturalCoatings-ROPAQUE® OP-96, The All Purpose Pigment”, April 1997 availablefrom Rohm and Haas Company, Philadelphia, Pa. at page 1, which is herebyincorporated by reference.

The particles 18 according to the present invention can also be formedfrom semisynthetic, organic polymeric materials and natural polymericmaterials. As used herein, a “semisynthetic material” is a chemicallymodified, naturally occurring material. Suitable semisynthetic, organicpolymeric materials from which the particles 18 can be formed include,but are not limited to, cellulosics, such as methylcellulose andcellulose acetate; and modified starches, such as starch acetate andstarch hydroxyethyl ethers. Suitable natural polymeric materials fromwhich the particles 18 can be formed include, but are not limited to,polysaccharides, such as starch; polypeptides, such as casein; andnatural hydrocarbons, such as natural rubber and gutta percha.

In one non-limiting embodiment of the present invention, the polymericparticles 18 are formed from hydrophobic polymeric materials to reduceor limit moisture absorption by the coated strand. Non-limiting examplesof such hydrophobic polymeric materials include but are not limited topolyethylene, polypropylene, polystyrene and polymethylmethacrylate.Non-limiting examples of polystyrene copolymers include ROPAQUE®HP-1055, ROPAQUE® OP-96, ROPAQUE® HP-543P, and ROPAQUE® OP-62 LOpigments (each discussed above).

In another non-limiting embodiment of the present invention, polymericparticles 18 are formed from polymeric materials having a glasstransition temperature (T_(g)) and/or melting point greater than 25° C.and preferably greater than 50° C.

In still another non-limiting embodiment of the present invention, theparticles 18 can be hollow particles formed from materials selected frompolymeric and non-polymeric inorganic materials, polymeric andnon-polymeric organic materials, composite materials, and mixtures ofany of the foregoing. Non-limiting examples of suitable materials fromwhich the hollow particles can be formed are described above.Non-limiting examples of a hollow polymeric particle useful in presentinvention are ROPAQUE® HP-1055, ROPAQUE® OP-96, ROPAQUE® HP-543P, andROPAQUE® OP-62 LO pigments (each discussed above). For othernon-limiting examples of hollow particles that can be useful in thepresent invention see H. Katz et al. (Ed.) (1987) at pages 437-452,which are specifically incorporated by reference herein.

The particles 18 useful in the coating composition present invention canbe present in a dispersion, suspension or emulsion in water. Othersolvents, such as mineral oil or alcohol (preferably less than 5 weightpercent), can be included in the dispersion, suspension or emulsion, ifdesired. A non-limiting example of a preferred dispersion of particlesformed from an inorganic material is ORPAC BORON NITRIDERELEASECOAT-CONC, which is a dispersion of 25 weight percent boronnitride particles in water and is commercially available from ZYPCoatings, Inc. of Oak Ridge, Tennessee. “ORPAC BORON NITRIDERELEASECOAT-CONC”, a technical bulletin of ZYP Coatings, Inc., isspecifically incorporated by reference herein. According to thistechnical bulletin, the boron nitride particles in this product have anaverage particle size of less than 3 micrometers and include 1 percentof magnesium-aluminum silicate to bind the boron nitride particles tothe substrate to which the dispersion is applied. Independent testing ofthe ORPAC BORON NITRIDE RELEASECOAT-CONC 25 boron nitride using theBeckman Coulter LS 230 particle size analyzer found an average particlesize of 6.2 micrometers, with particles ranging from submicrometer to 35micrometers and having the following distribution of particles:

% > 10 50 90 Size (μm) 10.2 5.5 2.4According to this distribution, ten percent of the ORPAC BORON NITRIDERELEASECOAT-CONC 25 boron nitride particles that were measured had anaverage particle size greater than 10.2 micrometers.

Other useful products which are commercially available from ZYP Coatingsinclude BORON NITRIDE LUBRICOAT® paint, and BRAZE STOP and WELD RELEASEproducts. Specific, non-limiting examples of emulsions and dispersionsof synthetic polymeric particles formed from acrylic polymers andcopolymers include: RHOPLEX® B-85 acrylic emulsion (discussed above),RHOPLEX® GL-623¹⁰ which is an all acrylic firm polymer emulsion having asolids content of 45 percent by weight and a glass transitiontemperature of 98° C.; EMULSION E-2321¹¹ which is a hard, methacrylatepolymer emulsion having a solids content of 45 percent by weight and aglass transition temperature of 105° C.; ROPAQUE® OP-96 and ROPAQUE®HP-543P (discussed above), which are supplied as a dispersion having aparticle size of 0.55 micrometers and a solids content of 30.5 percentby weight; ROPAQUE® OP-62 LO (discussed above), which is supplied as adispersion having a particles size of 0.40 micrometers and a solidscontent of 36.5 percent by weight; and ROPAQUE® HP-1055 (discussedabove), which is supplied as a dispersion having a solids content of26.5 percent by weight; all of which are commercially available fromRohm and Haas Company of Philadelphia, Pa.

¹⁰See product property sheet entiled: “Rhoplex® GL-623,Self-Crosslinking Acrylic Binder of Industrial Nonwovens, March 1997available from Rohm and Haas Company, Philadelphia, Pa., which is herebyIncorporated by reference.

¹¹See product property sheet entitled: “Building Products IndustrialCoatings-Emulsion E-2321”, 1990, available from Rohm and Haas Company,Philadelphia, Pa., which is hereby incorporated by reference.

In a particularly preferred embodiment of the present invention, thecoating composition comprises a mixture of at least one inorganicparticle, particularly boron nitride, and more particularly a boronnitride available under the tradename POLARTHERM® and/or ORPAC BORONNITRIDE RELEASECOAT-CONC, and at least one thermoplastic material,particularly a copolymer of styrene and an acrylic monomer, and moreparticularly a copolymer available under the tradename ROPAQUE®.

The particles 18 are selected to achieve an average particle size 19sufficient to effect the desired spacing between adjacent fibers. Forexample, the average size 19 of the particles 18 incorporated into asizing composition applied to fibers 12 to be processed on air-jet loomsis preferably selected to provide sufficient spacing between at leasttwo adjacent fibers to permit air-jet transport of the fiber strand 10across the loom. As used herein, “air-jet loom” means a type of loom inwhich the fill yarn (weft) is inserted into the warp shed by a blast ofcompressed air from one or more air jet nozzles in a manner well knownto those skilled in the art. In another example, the average size 19 ofthe particles 18 incorporated into a sizing composition applied tofibers 12 to be impregnated with a polymeric matrix material is selectedto provide sufficient spacing between at least two adjacent fibers topermit good wet-out and wet-through of the fiber strand 10.

Although not limiting in the present invention, the particles 18preferably have an average size, measured using laser scatteringtechniques, of no greater than 1000 micrometers, more preferably 0.001to 100 micrometers, and most preferably an average size of from 0.1 to25 micrometers.

In a specific, non-limiting embodiment of the present invention, theaverage particle size 19 of the particles 18 is at least 0.1micrometers, preferably at least 0.5 micrometers, and ranges from 0.1micrometers to 5 micrometers and preferably from 0.5 micrometers to 2micrometers. In an embodiment of the present invention, the particles 18have an average particle size 19 that is generally smaller than theaverage diameter of the fibers 12 to which the coating composition isapplied. It has been observed that twisted yarns made from fiber strands10 having a layer 14 of a residue of a primary sizing compositioncomprising particles 18 having average particles sizes 19 discussedabove can advantageously provide sufficient spacing between adjacentfibers 23, 25 to permit air-jet weavability (i.e., air-jet transportacross the loom) while maintaining the integrity of the fiber strand 10and providing acceptable wet-through and wet-out characteristics whenimpregnated with a polymeric matrix material.

In another specific, non-limiting embodiment of the present invention,the average particles size 19 of particles 18 is at least 3 micrometers,preferably at least 5 micrometers, and ranges from 3 to 1000micrometers, preferably 5 to 1000 micrometers, and more preferably 10 to25 micrometers. It is also preferred in this embodiment that the averageparticle size 19 of the particles 18 corresponds generally to theaverage nominal diameter of the glass fibers. It has been observed thatfabrics made with strands coated with particles falling within the sizesdiscussed above exhibit good wet-through and wet-out characteristicswhen impregnated with a polymeric matrix material.

It will be recognized by one skilled in the art that mixtures of one ormore particles 18 having different average particle sizes 19 can beincorporated into the coating composition in accordance with the presentinvention to impart the desired properties and processingcharacteristics to the fiber strands 10 and to the products subsequentlymade therefrom. More specifically, different sized particles can becombined in appropriate amounts to provide strands having good air-jettransport properties as well to provide a fabric exhibiting good wet-outand wet-through characteristics.

Fibers are subject to abrasive wear by contact with asperities ofadjacent fibers and/or other solid objects or materials which the glassfibers contact during forming and subsequent processing, such as weavingor roving. “Abrasive wear”, as used herein, means scraping or cuttingoff of bits of the fiber surface or breakage of fibers by frictionalcontact with particles, edges or entities of materials which are hardenough to produce damage to the fibers. See K. Ludema at page 129, whichis specifically incorporated by reference herein. Abrasive wear of fiberstrands causes detrimental effects to the fiber strands, such as strandbreakage during processing and surface defects in products such as wovencloth and composites, which increases waste and manufacturing cost.

In the forming step, for example, fibers, particularly glass fibers,contact solid objects such as a metallic gathering shoe and a traverseor spiral before being wound into a forming package. In fabric assemblyoperations, such as knitting or weaving, the glass fiber strand contactssolid objects such as portions of the fiber assembly apparatus (e.g. aloom or knitting device) which can abrade the surfaces 16 of thecontacting glass fibers 12. Examples of portions of a loom which contactthe glass fibers include air jets and shuttles. Surface asperities ofthese solid objects that have a hardness value greater than that of theglass fibers can cause abrasive wear of the glass fibers. For example,many portions of the twist frame, loom and knitting device are formedfrom metallic materials such as steel, which has a Mohs' hardness up to8.5¹². Abrasive wear of glass fiber strands from contact with asperitiesof these solid objects causes strand breakage during processing andsurface defects in products such as woven cloth and composites, whichincreases waste and manufacturing cost.

¹² Handbook of Chemistry and Physics at page F-22.

To minimize abrasive wear, in one non-limiting embodiment of the presentinvention, the particles 18 have a hardness value which does not exceed,i.e., is less than or equal to, a hardness value of the glass fiber(s).The hardness values of the particles and glass fibers can be determinedby any conventional hardness measurement method, such as Vickers orBrinell hardness, but is preferably determined according to the originalMohs' hardness scale which indicates the relative scratch resistance ofthe surface of a material on a scale of one to ten. The Mohs' hardnessvalue of glass fibers generally ranges from 4.5 to 6.5, and is generally6. R. Weast (Ed.), Handbook of Chemistry and Physics, CRC Press (1975)at page F-22, which is specifically incorporated by reference herein. Inthis embodiment, the Mohs' hardness value of the particles 18 preferablyranges from 0.5 to 6. The Mohs' hardness values of several non-limitingexamples of particles formed from inorganic materials suitable for usein the present invention are given in Table A below.

TABLE A Mohs' hardness Particle material (original scale) boron nitride2¹³ graphite 0.5-1¹⁴ molybdenum disulfide 1¹⁵ talc 1-1.5¹⁶ mica2.8-3.2¹⁷ kaolinite 2.0-2.5¹⁸ gypsum 1.6-2¹⁹ calcite (calcium carbonate)3²⁰ calcium fluoride 4²¹ zinc oxide 4.5²² aluminum 2.5²³ copper 2.5-3²⁴iron 4-5²⁵ gold 2.5-3²⁶ nickel 5²⁷ palladium 4.8²⁸ platinum 4.3²⁹ silver2.5-4³⁰ zinc sulfide 3.5-4³¹ ¹³K. Ludema, Friction, Wear, Lubrication,(1996) at page 27, which is hereby incorporated by reference. ¹⁴R. Weast(Ed.), Handbook of Chemistry and Physics, CRC Press (1975) at page F-22.¹⁵R. Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed. 1993)at page 793, which is hereby incorporated by reference. ¹⁶Hawley'sCondensed Chemical Dictionary, (12th Ed. 1993) at page 1113, which ishereby incorporated by reference. ¹⁷Hawley's Condensed ChemicalDictionary, (12th Ed. 1993) at page 784, which is hereby incorporated byreference. ¹⁸Handbook of Chemistry and Physics at page F-22. ¹⁹Handbookof Chemistry and Physics at page F-22. ²⁰Friction, Wear, Lubrication atpage 27. ²¹Friction, Wear, Lubrication at page 27. ²²Friction, Wear,Lubrication at page 27. ²³Friction, Wear, Lubrication at page 27.²⁴Handbook of Chemistry and Physics at page F-22. ²⁵Handbook ofChemistry and Physics at page F-22. ²⁶Handbook of Chemistry and Physicsat page F-22. ²⁷Handbook of Chemistry and Physics at page F-22.²⁸Handbook of Chemistry and Physics at page F-22. ²⁹Handbook ofChemistry and Physics at page F-22. ³⁰Handbook of Chemistry and Physicsat page F-22. ³¹R. Weast (Ed.), Handbook of Chemistry and Physics, CRCPress (71^(st) Ed. 1990) at page 4-158.

As mentioned above, the Mohs' hardness scale relates to the resistanceof a material to scratching. The instant invention therefore furthercontemplates particles that have a hardness at their surface that isdifferent from the hardness of the internal portions of the particlebeneath its surface. More specifically, and as discussed above, thesurface of the particle can be modified in any manner well known in theart, including, but not limited to, chemically changing the particle'ssurface characteristics using techniques known in the art such that thesurface hardness of the particle is less than or equal to the hardnessof the glass fibers while the hardness of the particle beneath thesurface is greater than the hardness of the glass fibers. As anotheralternative, a particle can be formed from a primary material that iscoated, clad or encapsulated with one or more secondary materials toform a composite material that has a softer surface. Alternatively, aparticle can be formed from a primary material that is coated, clad orencapsulated with a differing form of the primary material to form acomposite material that has a softer surface.

In one example, and without limiting the present invention, an inorganicparticle formed from an inorganic material such as silicon carbide oraluminum nitride can be provided with a silica, carbonate or nanoclaycoating to form a useful composite particle. In another embodiment, theinorganic particles can be reacted with a coupling agent havingfunctionality capable of covalently bonding to the inorganic particlesand functionality capable of crosslinking into the film-forming materialor crosslinkable resin. Such coupling agents are described in U.S. Pat.No. 5,853,809 at column 7, line 20 through column 8, line 43, which isincorporated herein by reference. Useful silane coupling agents includeglycidyl, isocyanato, amino or carbamyl functional silane couplingagents. In another non-limiting example, a silane coupling agent withalkyl side chains can be reacted with the surface of an inorganicparticle formed from an inorganic oxide to provide a useful compositeparticle having a “softer” surface. Other examples include cladding,encapsulating or coating particles formed from non-polymeric orpolymeric materials with differing non-polymeric or polymeric materials.A specific non-limiting example of such composite particles is DUALITE,which is a synthetic polymeric particle coated with calcium carbonatethat is commercially available from Pierce and Stevens Corporation ofBuffalo, N.Y.

In one embodiment of the present invention, the particles 18 arethermally conductive, i.e., preferably have a thermal conductivity of atleast 0.2 Watts per meter K, more preferably at least 0.5 Watts permeter K, measured at a temperature of 300 K. In a non-limitingembodiment, the particles 18 have a thermal conductivity of at least 1Watt per meter K, more preferably at least 5 Watts per meter K, measuredat a temperature of 300 K. In a preferred embodiment, the thermalconductivity of the particles is at least 25 Watts per meter K, morepreferably at least 30 Watts per meter K, and even more preferably atleast 100 Watts per meter K, measured at a temperature of 300 K. Inanother preferred embodiment, the thermal conductivity of the particlesranges from 5 to 2000 Watts per meter K, preferably from 25 to 2000Watts per meter K, more preferably from 30 to 2000 Watts per meter K,and most preferably from 100 to 2000 Watts per meter K, measured at atemperature of 300 K. As used herein, “thermal conductivity” means theproperty of the particle that describes its ability to transfer heatthrough itself. See R. Lewis, Sr., Hawley's Condensed ChemicalDictionary, (12th Ed. 1993) at page 305, which is specificallyincorporated by reference herein.

The thermal conductivity of a material can be determined by any methodknown to one skilled in the art. For example, if the thermalconductivity of the material to be tested ranges from 0.001 Watts permeter K to 100 Watts per meter K, the thermal conductivity of thematerial can be determined using the preferred guarded hot plate methodaccording to ASTM C-177-85 (which is specifically incorporated byreference herein) at a temperature of 300 K. If the thermal conductivityof the material to be tested ranges from 20 Watts per meter K to 1200Watts per meter K, the thermal conductivity of the material can bedetermined using the guarded hot flux sensor method according to ASTMC-518-91 (which is specifically incorporated by reference herein). Inother words, the guarded hot plate method is to be used if the thermalconductivity ranges from 0.001 Watts per meter K to 20 Watts per meterK. If the thermal conductivity is over 100 Watts per meter K, theguarded hot flux sensor method is to be used. For ranges from 20 to 100Watts per meter K, either method can be used.

In the guarded hot plate method, a guarded hot plate apparatuscontaining a guarded heating unit, two auxiliary heating plates, twocooling units, edge insulation, a temperature controlled secondaryguard, and a temperature sensor read-out system is used to test twoessentially identical samples. The samples are placed on either side ofthe guarded heating unit with the opposite faces of the specimens incontact with the auxiliary heating units. The apparatus is then heatedto the desired test temperature and held for a period of time requiredto achieve thermal steady state. Once the steady state condition isachieved, the heat flow (Q) passing through the samples and thetemperature difference (ΔT) across the samples are recorded. The averagethermal conductivity (K_(TC)) of the samples is then calculated usingthe following formula (1):K _(TC) =Q L/A·ΔT  (I)wherein L is the average thickness of the samples and A is the averageof the combined area of the samples.

It is believed that the materials with higher thermal conductivity willmore quickly dissipate the heat generated during a drilling operationfrom the hole area, resulting in prolonged drill tip life. The thermalconductivity of selected material in Table A is included in Table B.

Although not required, in another embodiment useful in the presentinvention, the particles are electrically insulative or have highelectrical resistivity, i.e., have an electrical resistivity greaterthan 1000 microohm-cm. Use of particles having high electricalresistivity is preferred for conventional electronic circuit boardapplications to inhibit loss of electrical signals due to conduction ofelectrons through the reinforcement. For specialty applications, such ascircuit boards for microwave, radio frequency interference andelectromagnetic interference applications, particles having highelectrical resistivity are not required. The electrical resistance ofselected materials in Table A is included in Table B.

TABLE B Inorganic Thermal conductivity Electrical Resistance Mohs'hardness Solid Material (W/m K at 300K) (micro ohm-centimeters)(original scale) boron nitride 200³² 1.7 × 10¹⁹ ³³ 2³⁴   boron phosphide350³⁵ — 9.5³⁶ aluminum phosphide 130³⁷ — — aluminum nitride 200³⁸greater than 10¹⁹ ³⁹ 9⁴⁰   gallium nitride 170⁴¹ — — gallium phosphide100⁴² — — silicon carbide 270⁴³ 4 × 10⁵ to 1 × 10⁶ ⁴⁴ greater than 9⁴⁵silicon nitride  30⁴⁶ 10¹⁹ to 10²⁰ ⁴⁷ 9⁴⁸   beryllium oxide 240⁴⁹ —9⁵⁰   zinc oxide 26  — 4.5⁵¹ zinc sulfide  25⁵² 2.7 × 10⁵ to 1.2 × 10¹²⁵³ 3.5-4⁵⁴ diamond 2300⁵⁵  2.7 × 10⁸ ⁵⁶ 10⁵⁷  silicon  84⁵⁸ 10.0⁵⁹ 7⁶⁰  graphite up to 2000⁶¹  100⁶² 0.5-1⁶³ molybdenum 138⁶⁴  5.2⁶⁵ 5.5⁶⁸platinum  69⁶⁷ 10.6⁶⁸ 4.3⁶⁹ palladium  70⁷⁰ 10.8⁷¹ 4.8⁷² tungsten 200⁷³ 5.5⁷⁴ 7.5⁷⁵ nickel  92⁷⁶  6.8⁷⁷ 5⁷⁸   aluminum 205⁷⁹  4.3⁸⁰ 2.5⁸¹chromium  66⁸²   20⁸³ 9.0⁸⁴ copper 398⁸⁵  1.7⁸⁶ 2.5-3⁸⁷ gold 297⁸⁸ 2.2⁸⁹ 2.5-3⁹⁰ iron  74.5⁹¹   9⁹²   4-5⁹³ silver 418⁹⁴  1.6⁹⁵ 2.5-4⁹⁶³²G. Slack, “Nonmetallic Crystals with High Thermal Conductivity, J.Phys. Chem. Solids (1973) Vol. 34, p. 322, which is hereby incorporatedby reference. ³³A. Weimer (Ed.), Carbide, Nitride and Boride MaterialsSynthesis and Processing, (1997) at page 654. ³⁴Friction, Wear,Lubrication at page 27. ³⁵G. Slack, “Nonmetallic Crystals with HighThermal Conductivity, J. Phys. Chem. Solids (1973) Vol. 34, p. 325,which is hereby incorporated by reference. ³⁶R. Lewis, Sr., Hawley'sCondensed Chemical Dictionary, (12th Ed. 1993) at page 164, which ishereby incorporated by reference. ³⁷G. Slack, “Nonmetallic Crystals withHigh Thermal Conductivity, J. Phys. Chem. Solids (1973) Vol. 34, p. 333,which is hereby incorporated by reference. ³⁸G. Slack, “NonmetallicCrystals with High Thermal Conductivity, J. Phys. Chem. Solids (1973)Vol. 34, p. 329, which is hereby incorporated by reference. ³⁹A. Weimer(Ed.), Carbide, Nitride and Boride Materials Synthesis and Processing,(1997) at page 654. ⁴⁰Friction, Wear, Lubrication at page 27. ⁴¹G.Slack, “Nonmetallic Crystals with High Thermal Conductivity, J. Phys.Chem. Solids (1973) Vol. 34, p. 333 ⁴²G. Slack, “Nonmetallic Crystalswith High Thermal Conductivity, J. Phys. Chem. Solids (1973) Vol. 34, p.321, which is hereby incorporated by reference. ⁴³MicroelectronicsPackaging Handbook at page 36, which is hereby incorporated byreference. ⁴⁴A. Weimer (Ed.), Carbide, Nitride and Boride MaterialsSynthesis and Processing, (1997) at page 653, which is herebyincorporated by reference. ⁴⁵Friction, Wear, Lubrication at page 27.⁴⁶Microelectronics Packaging Handbook at page 36, which is herebyincorporated by reference. ⁴⁷A. Weimer (Ed.), Carbide, Nitride andBoride Materials Synthesis and Processing, (1997) at page 654.⁴⁸Friction, Wear, Lubrication at page 27. ⁴⁹Microelectronics PackagingHandbook at page 905, which is hereby incorporated by reference.⁵⁰Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at page 141,which is hereby incorporated by reference. ⁵¹Friction, Wear, Lubricationat page 27. ⁵²Handbook of Chemistry and Physics, CRC Press (1975) atpages 12-54. ⁵³Handbook of Chemistry and Physics, CRC Press (71st Ed.1990) at pages 12-63, which is hereby incorporated by reference.⁵⁴Handbook of Chemistry and Physics, CRC Press (71st Ed. 1990) at page4-158, which is hereby incorporated by reference. ⁵⁵MicroelectronicsPackaging Handbook at page 36. ⁵⁶Handbook of Chemistry and Physics, CRCPress (71st Ed. 1990) at pages 12-63, which is hereby incorporated byreference. ⁵⁷Handbook of Chemistry and Physics at page F-22.⁵⁸Microelectronics Packaging Handbook at page 174. ⁵⁹Handbook ofChemistry and Physics at page F-166, which is hereby incorporated byreference. ⁶⁰Friction, Wear, Lubrication at page 27. ⁶¹G. Slack,“Nonmetallic Crystals with High Thermal Conductivity, J. Phys. Chem.Solids (1973) Vol. 34, p. 322, which is hereby incorporated byreference. ⁶²See W. Callister, Materials Science and Engineering AnIntroduction, (2d ed. 1991) at page 637, which is hereby incorporated byreference. ⁶³Handbook of Chemistry and Physics at page F-22.⁶⁴Microelectronics Packaging Handbook at page 174. ⁶⁵MicroelectronicsPackaging Handbook at page 37. ⁶⁶According to “Web Elements”http://www.shef.ac.uk/-chem/web-elents/nofr-image-l/hardness-minerals-l.html(Feb. 26, 1998). ⁶⁷Microelectronics Packaging Handbook at page 174.⁶⁸Microelectronics Packaging Handbook at page 37. ⁶⁹Handbook ofChemistry and Physics at page F-22. ⁷⁰Microelectronics PackagingHandbook at page 37. ⁷¹Microelectronics Packaging Handbook at page 37.⁷²Handbook of Chemistry and Physics at page F-22. ⁷³MicroelectronicsPackaging Handbook at page 37. ⁷⁴Microelectronics Packaging Handbook atpage 37. ⁷⁵According to “Web Elements”http://www.shef.ac.uk/-chem/web-elents/nofr-image-l/hardness-minerals-l.html(Feb. 26, 1998). ⁷⁶Microelectronics Packaging Handbook at page 174.⁷⁷Microelectronics Packaging Handbook at page 37. ⁷⁸Handbook ofChemistry and Physics at page F-22. ⁷⁹Microelectronics PackagingHandbook at page 174. ⁸⁰Microelectronics Packaging Handbook at page 37.⁸¹Friction, Wear, Lubrication at page 27. ⁸²Microelectronics PackagingHandbook at page 37. ⁸³Microelectronics Packaging Handbook at page 37.⁸⁴Handbook of Chemistry and Physics at page F-22. ⁸⁵MicroelectronicsPackaging Handbook at page 174. ⁸⁶Microelectronics Packaging Handbook atpage 37. ⁸⁷Handbook of Chemistry and Physics, at page F-22.⁸⁸Microelectronics Packaging Handbook at page 174. ⁸⁹MicroelectronicsPackaging Handbook at page 37. ⁹⁰Handbook of Chemistry and Physics atpage F-22. ⁹¹Microelectronics Packaging Handbook at page 174. ⁹²Handbookof Chemistry and Physics, CRC Press (1975) at page D-171, which ishereby incorporated by reference. ⁹³Handbook of Chemistry and Physics atpage F-22. ⁹⁴Microelectronics Packaging Handbook at page 174.⁹⁵Microelectronics Packaging Handbook at page 37. ⁹⁶Handbook ofChemistry and Physics at page F-22.

It will be appreciated by one skilled in the art that particles 18 ofthe coating composition of the present invention can include anycombination or mixture of particles 18 discussed above. Morespecifically, and without limiting the present invention, the particles18 can include any combination of additional particles made from any ofthe materials described above. Thus, all particles 18 do not have to bethe same; they can be chemically different and/or chemically the samebut different in configuration or properties. The additional particlescan generally comprise up to half of the particles 18, preferably up to15 percent of the particles 18.

In one embodiment, the particles 18 comprise 0.001 to 99 weight percentof the coating composition on a total solids basis, preferably 50 to 99weight percent, and more preferably 75 to 99 weight percent. In thisembodiment, particularly preferred coatings include, but are not limitedto: i) coatings comprising an organic component and lamellar particleshaving a thermal conductivity of at least 1 Watt per meter K at atemperature of 300 K; ii) coatings comprising an organic component andnon-hydratable, lamellar particles; iii) coatings comprising at leastone boron-free lamellar particle having a thermal conductivity of atleast 1 Watt per meter K at a temperature of 300 K; iv) a residue of anaqueous composition comprising lamellar particles having a thermalconductivity of at least 1 Watt per meter K at a temperature of 300 K,i.e., lamellar particles on the fiber; and v) a residue of an aqueouscomposition comprising alumina-free, non-hydratable particles having athermal conductivity of at least 1 Watt per meter K at a temperature of300 K, i.e., alumina-free, non-hydratable particles on the fiber.

In another embodiment, the particles 18 comprise 0.001 to 99 weightpercent of the coating composition on a total solids basis, preferably 1to 80 weight percent, and more preferably 1 to 40 weight percent. Inaddition, in the particular embodiment wherein the particles 18 arenon-hydratable inorganic particles, the particles preferably comprise 1to 50 weight percent of the coating composition on a total solids basis,and more preferably up to 25 weight percent of the coating composition.

In yet another embodiment, the particles 18 comprise greater than 20weight percent of the coating composition on a total solids basis,preferably ranging from 20 to 99 weight percent, more preferably rangingfrom 25 to 80 weight percent, and most preferably ranging from 50 to 60weight percent. In this embodiment, particularly preferred coatingsinclude resin compatible coating compositions comprising greater than 20weight percent on a total solids basis of at least one particle selectedfrom inorganic particles, organic hollow particles and compositeparticles, the at least one particle having a Mohs' hardness value whichdoes not exceed the Mohs' hardness value of at least one glass fiber.

In another embodiment, the particles 18 comprise 1 to 80 weight percentof the coating composition on a total solids basis, preferably 1 to 60weight percent. In one embodiment, the coating composition contains 20to 60 weight percent of particles 18 on total solids basis, andpreferably 35 to 55 weight percent, and more preferably 30 to 50 weightpercent. Preferred coatings further to this embodiment include a resincompatible coating comprising (a) a plurality of discrete particlesformed from materials selected from non-heat expandable organicmaterials, inorganic polymeric materials, non-heat expandable compositematerials and mixtures thereof, the particles having an average particlesize sufficient to allow strand wet out without application of externalheat; (b) at least one lubricious material different from said pluralityof discrete particles; and (c) at least one film-forming material.

In addition to the particles, the coating composition preferablycomprises one or more film-forming materials, such as organic, inorganicand natural polymeric materials. Useful organic materials include butare not limited to polymeric materials selected from synthetic polymericmaterials, semisynthetic polymeric materials, natural polymericmaterials, and mixtures of any of the foregoing. Synthetic polymericmaterials include but are not limited to thermoplastic materials andthermosetting materials. Preferably, the polymeric film-formingmaterials form a generally continuous film when applied to the surface16 of the glass fibers.

Generally, the amount of film-forming materials ranges from 1 to 99weight percent of the coating composition on a total solids basis. Inone embodiment, the amount of film-forming materials preferably rangesfrom 1 to 50 weight percent, and more preferably from 1 to 25 weightpercent. In another embodiment, the amount of film-forming materialsranges from 20 to 99 weight percent, and more preferably ranges from 60to 80 weight percent.

In another embodiment, the amount of film-forming materials preferablyranges from 20 to 75 weight percent of the coating composition on atotal solids basis, and more preferably 40 to 50 weight percent. In thisembodiment, particularly preferred coatings comprise a film-formingmaterial and greater than 20 weight percent on a total solids basis ofat least one particle selected from inorganic particles, organic hollowparticles and composite particles, the at least one particle having aMohs' hardness value which does not exceed the Mohs' hardness value ofat the least one glass fiber.

In yet another embodiment, the amount of polymeric film-formingmaterials can range from 1 to 60 weight percent of the coatingcomposition on a total solids basis, preferably 5 to 50 weight percent,and more preferably 10 to 30 weight percent Preferred coatings furtherto this embodiment include a resin compatible coating comprising (a) aplurality of discrete particles formed from materials selected fromnon-heat expandable organic materials, inorganic polymeric materials,non-heat expandable composite materials and mixtures thereof, theparticles having an average particle size sufficient to allow strand wetout without application of external heat; (b) at least one lubriciousmaterial different from said plurality of discrete particles; and (c) atleast one film-forming material.

In one non-limiting embodiment of the present invention, thermosettingpolymeric film-forming materials are the preferred polymericfilm-forming materials for use in the coating composition for coatingglass fiber strands. Such materials are compatible with thermosettingmatrix materials used as laminates for printed circuit boards, such asFR-4 epoxy resins, which are polyfunctional epoxy resins and in oneparticular embodiment of the invention is a difunctional brominatedepoxy resins. See Electronic Materials Handbook™, ASM International(1989) at pages 534-537, which are specifically incorporated byreference herein.

Useful thermosetting materials include thermosetting polyesters, epoxymaterials, vinyl esters, phenylics, aminoplasts, thermosettingpolyurethanes, carbamate-functional polymers and mixtures of any of theforegoing. Suitable thermosetting polyesters include STYPOL polyestersthat are commercially available from Cook Composites and Polymers ofKansas City, Mo., and NEOXIL polyesters that are commercially availablefrom DSM B.V. of Como, Italy.

A non-limiting example of a thermosetting polymeric material is an epoxymaterial. Useful epoxy materials contain at least one epoxy or oxiranegroup in the molecule, such as polyglycidyl ethers of polyhydricalcohols or thiols. Examples of suitable epoxy film-forming polymersinclude EPON® 826 and EPON® 880 epoxy resins, commercially availablefrom Shelf Chemical Company of Houston, Tex.

Useful carbamate-functional polymers include carbamate-functionalacrylic polymers in which pendent and/or terminal carbamate functionalgroups can be incorporated into the acrylic polymer by copolymerizingthe acrylic monomer with a carbamate functional vinyl monomer, such as acarbamate functional alkyl ester of methacrylic acid. As is preferred,carbamate groups can also be incorporated into the acrylic polymer by a“transcarbamoylation” reaction in which a hydroxyl functional acrylicpolymer is reacted with a low molecular weight carbamate derived from analcohol or a glycol ether. The carbamate groups exchange with thehydroxyl groups yielding the carbamate functional acrylic polymer andthe original alcohol or glycol ether. The carbamate functionalgroup-containing acrylic polymer typically has a Mn ranging from 500 to30,000 and a calculated carbamate equivalent weight typically within therange of 15 to 150 based on equivalents of reactive carbamate groups.

It should be understood that the preferred carbamate functionalgroup-containing polymers typically contain residual hydroxyl functionalgroups which provide additional crosslinking sites. Preferably, thecarbamate/hydroxyl functional group-containing polymer has a residualhydroxyl value ranging from 0.5 to 10 mg KOH per gram.

Useful thermoplastic polymeric materials include vinyl polymers,thermoplastic polyesters, polyolefins, polyamides (e.g. aliphaticpolyamides or aromatic polyamides such as aramid), thermoplasticpolyurethanes, acrylic polymers (such as polyacrylic acid), and mixturesof any of the foregoing.

In another non-forming embodiment of the present invention, thepreferred polymeric film-forming material is a vinyl polymer. Usefulvinyl polymers in the present invention include, but are not limited to,polyvinyl pyrrolidones such as PVP K-15, PVP K-30, PVP K-60 and PVPK-90, each of which is commercially available from InternationalSpecialty Products Chemicals of Wayne, N.J. Other suitable vinylpolymers include RESYN 2828 and RESYN 1037 vinyl acetate copolymeremulsions which are commercially available from National Starch andChemical of Bridgewater, N.J., other polyvinyl acetates such as arecommercially available from H. B. Fuller and Air Products and ChemicalsCompany of Allentown, Pa., and polyvinyl alcohols which are alsoavailable from Air Products and Chemicals Company.

Thermoplastic polyesters useful in the present invention includeDESMOPHEN 2000 and DESMOPHEN 2001KS, both of which are commerciallyavailable from Bayer Corp. of Pittsburgh, Pa. Preferred polyestersinclude RD-847A polyester resin, which is commercially available fromBorden Chemicals of Columbus, Ohio, and DYNAKOLL Si 100 chemicallymodified rosin, which is commercially available from Eka Chemicals AB,Sweden. Useful polyamides include the VERSAMID products that arecommercially available from Cognis Corp. of Cincinnati, Ohio, andEUREDOR products that are available from Ciba Geigy, Belgium. Usefulthermoplastic polyurethanes include WITCOBOND® W-290H, which iscommercially available from CK Witco Corp. of Greenwich, Conn., andRUCOTHANE® 2011L polyurethane latex, which is commercially availablefrom Ruco Polymer Corp. of Hicksville, New York.

The coating compositions of the present invention can comprise a mixtureof one or more thermosetting polymeric materials with one or morethermoplastic polymeric materials. In one non-limiting embodiment of thepresent invention particularly useful for laminates for printed circuitboards, the polymeric materials of the aqueous sizing compositioncomprise a mixture of RD-847A polyester resin, PVP K-30 polyvinylpyrrolidone, DESMOPHEN 2000 polyester and VERSAMID polyamide. In analternative non-limiting embodiment suitable for laminates for printedcircuit boards, the polymeric materials of the aqueous sizingcomposition comprise PVP K-30 polyvinyl pyrrolidone, optionally combinedwith EPON 826 epoxy resin.

Semisynthetic polymeric materials suitable for use as polymericfilm-forming materials include but are not limited to cellulosics suchas hydroxypropylcellulose and modified starches such as KOLLOTEX 1250 (alow viscosity, low amylose potato-based starch etherified with ethyleneoxide) which is commercially available from AVEBE of The Netherlands.

Natural polymeric materials suitable for use as polymeric film-formingmaterials include but are not limited to starches prepared frompotatoes, corn, wheat; waxy maize, sago, rice, milo, and mixtures of anyof the foregoing.

It should be appreciated that depending on the nature of the starch, thestarch can function as both a particle 18 and/or a film-formingmaterial. More specifically, some starches will dissolve completely in asolvent, and in particular water, and function as a film formingmaterial while others will not completely dissolve and will maintain aparticular grain size and function as a particle 18. Although starches(both natural and semisynthetic) can be used in accordance with thepresent invention, the coating composition of the present invention ispreferably substantially free of starch materials. As used herein, theterm “substantially free of starch materials” means that the coatingcomposition comprises less than 50 weight percent on a total solidsbasis of the coating composition, preferably less than 35 weight ofstarch materials. More preferably, the coating composition of thepresent invention is essentially free of starch materials. As usedherein, the term “essentially free of starch materials” means that thecoating composition comprises less than 20 weight percent on a totalsolids basis of the coating composition, preferably less than weightpercent and more preferably is free of starch materials.

Typical primary sizing compositions containing starches that are appliedto fiber strands to be incorporated into laminates for printed circuitboards are not resin compatible and must be removed prior toincorporation into the polymeric matrix material. As previouslydiscussed, preferably the coating compositions of the present inventionare resin compatible and do not require removal from the fiber strandsor fibers prior to fabric processing. More preferably, the coatingcompositions of the present invention are compatible with matrixmaterials used to make printed circuit boards (discussed below) and mostpreferably are epoxy resin compatible.

The polymeric film-forming materials can be water soluble, emulsifiable,dispersible and/or curable. As used herein, “water soluble” means thatthe polymeric materials are capable of being essentially uniformlyblended and/or molecularly or ionically dispersed in water to form atrue solution. See Hawley's at page 1075, which is specificallyincorporated by reference herein. “Emulsifiable” means that thepolymeric materials are capable of forming an essentially stable mixtureor being suspended in water in the presence of an emulsifying agent. SeeHawley's at page 461, which is specifically incorporated by referenceherein. Non-limiting examples of suitable emulsifying agents are setforth below. “Dispersible” means that any of the components of thepolymeric materials are capable of being distributed throughout water asfinely divided particles, such as a latex. See Hawley's at page 435,which is specifically incorporated by reference herein. The uniformityof the dispersion can be increased by the addition of wetting,dispersing or emulsifying agents (surfactants), which are discussedbelow. “Curable” means that the polymeric materials and other componentsof the sizing composition are capable of being coalesced into a film orcrosslinked to each other to change the physical properties of thepolymeric materials. See Hawley's at page 331, which is specificallyincorporated by reference herein.

In addition to or in lieu of the film forming materials discussed above,the coating compositions of the present invention preferably comprisesone or more glass fiber coupling agents such as organo-silane couplingagents, transition metal coupling agents, phosphonate coupling agents,aluminum coupling agents, amino-containing Werner coupling agents, andmixtures of any of the foregoing. These coupling agents typically havedual functionality. Each metal or silicon atom has attached to it one ormore groups which can either react with or compatibilize the fibersurface and/or the components of the resin matrix. As used herein, theterm “compatibilize” means that the groups are chemically attracted, butnot bonded, to the fiber surface and/or the components of the coatingcomposition, for example by polar, wetting or solvation forces. In onenon-limiting embodiment, each metal or silicon atom has attached to itone or more hydrolyzable groups that allow the coupling agent to reactwith the glass fiber surface, and one or more functional groups thatallow the coupling agent to react with components of the resin matrix.Examples of hydrolyzable groups include:

the monohydroxy and/or cyclic C₂-C₃ residue of a 1,2- or 1,3 glycol,wherein R¹ is C₁-C₃ alkyl; R² is H or C₁-C₄ alkyl; R³ and R⁴ areindependently selected from H, C₁-C₄ alkyl or C₆-C₈ aryl; and R⁵ isC₄-C₇ alkylene. Examples of suitable compatibilizing or functionalgroups include epoxy, glycidoxy, mercapto, cyano, allyl, alkyl,urethano, carbamate, halo, isocyanato, ureido, imidazolinyl, vinyl,acrylato, methacrylato, amino or polyamino groups.

Functional organo-silane coupling agents are preferred for use in thepresent invention. Examples of useful functional organo silane couplingagents include gamma-aminopropyltrialkoxysilanes,gamma-isocyanatopropyltriethoxysilane, vinyl-trialkoxysilanes,glycidoxypropyltrialkoxysilanes and ureidopropyltrialkoxysilanes.

Preferred functional organo-silane coupling agents include A-187gamma-glycidoxy-propyltrimethoxysilane, A-174gamma-methacryloxypropyltrimethoxysilane, A-1100gamma-aminopropyltriethoxysilane silane coupling agents, A-1108 aminosilane coupling agent and A-1160 gamma-ureidopropyltriethoxysilane (eachof which is commercially available from CK Witco Corporation ofTarrytown, New York). The organo silane coupling agent can be at leastpartially hydrolyzed with water prior to application to the fibers,preferably at a 1:1 stoichiometric ratio or, if desired, applied inunhydrolyzed form. The pH of the water can be modified by the additionof an acid or a base to initiate or speed the hydrolysis of the couplingagent as is well known in the art.

Suitable transition metal coupling agents include titanium, zirconium,yttrium and chromium coupling agents. Suitable titanate coupling agentsand zirconate coupling agents are commercially available from KenrichPetrochemical Company. Suitable chromium complexes are commerciallyavailable from E.I. DuPont de Nemours of Wilmington, Del. Theamino-containing Werner-type coupling agents are complex compounds inwhich a trivalent nuclear atom such as chromium is coordinated with anorganic acid having amino functionality. Other metal chelate andcoordinate type coupling agents known to those skilled in the art can beused herein.

The amount of coupling agent generally ranges from 1 to 99 weightpercent of the coating composition on a total solids basis. In oneembodiment, the amount of coupling agent ranges from 1 to 30 weightpercent of the coating composition on a total solids basis, preferably 1to 10 weight percent, and more preferably 2 to 8 weight percent.

The coating compositions of the present invention can further compriseone or more softening agents or surfactants that impart a uniform chargeto the surface of the fibers causing the fibers to repel from each otherand reducing the friction between the fibers, so as to function as alubricant. Although not required, preferably the softening agents arechemically different from other components of the coating composition.Such softening agents include cationic, non-ionic or anionic softeningagents and mixtures thereof, such as amine salts of fatty acids, alkylimidazoline derivatives such as CATION X, which is commerciallyavailable from Rhone Poulenc/Rhodia of Princeton, N.J., acid solubilizedfatty acid amides, condensates of a fatty acid and polyethylene imineand amide substituted polyethylene imines, such as EMERY® 6717, apartially amidated polyethylene imine commercially available from CognisCorporation of Cincinnati, Ohio. While the coating composition cancomprise up to 60 weight percent of softening agents, preferably thecoating composition comprises less than 20 weight percent and morepreferably less than 5 weight percent of the softening agents. For moreinformation on softening agents, see A. J. Hall, Textile Finishing, 2ndEd. (1957) at pages 108-115, which are specifically incorporated byreference herein.

The coating compositions of the present invention can further includeone or more lubricious materials that are chemically different from thepolymeric materials and softening agents discussed above to impartdesirable processing characteristics to the fiber strands duringweaving. Suitable lubricious materials can be selected from oils, waxes,greases, and mixtures of any of the foregoing. Non-limiting examples ofwax materials useful in the present invention include aqueous soluble,emulsifiable or dispersible wax materials such as vegetable, animal,mineral, synthetic or petroleum waxes, e.g. paraffin. Oils useful in thepresent invention include both natural oils, semisynthetic oils andsynthetic oils. Generally, the amount of wax or other lubriciousmaterial can range from 0 to 80 weight percent of the sizing compositionon a total solids basis, preferably from 1 to 50 weight percent, morepreferably from 20 to 40 weight percent, and most preferably from 25 to35 weight percent.

Preferred lubricious materials include waxes and oils having polarcharacteristics, and more preferably include highly crystalline waxeshaving polar characteristics and melting points above 35° C. and morepreferably above 45° C. Such materials are believed to improve thewet-out and wet-through of polar resins on fiber strands coated withsizing compositions containing such polar materials as compared to fiberstrands coated with sizing compositions containing waxes and oils thatdo not have polar characteristics. Preferred lubricious materials havingpolar characteristics include esters formed from reacting (1) amonocarboxlyic acid and (2) a monohydric alcohol. Non-limiting examplesof such fatty acid esters useful in the present invention include cetylpalmitate, which is preferred (such as is available from Stepan Companyof Maywood, N.J. as KESSCO 653 or STEPANTEX 653), cetyl myristate (alsoavailable from Stepan Company as STEPANLUBE 654), cetyl laurate,octadecyl laurate, octadecyl myristate, octadecyl palmitate andoctadecyl stearate. Other fatty acid ester, lubricious materials usefulin the present invention include trimethylolpropane tripelargonate,natural spermaceti and triglyceride oils, such as but not limited tosoybean oil, linseed oil, epoxidized soybean oil, and epoxidized linseedoil.

The lubricious materials can also include water-soluble polymericmaterials. Non-limiting examples of useful materials includepolyalkylene polyols and polyoxyalkylene polyols, such as MACOL E-300which is commercially available from BASF Corporation of Parsippany, NewJersey, and CARBOWAX 300 and CARBOWAX 400 which is commerciallyavailable from Union Carbide Corporation, Danbury, Conn. Anothernon-limiting example of a useful lubricious material is POLYOX WSR 301which is a poly(ethylene oxide) commercially available from UnionCarbide Corporation, Danbury, Conn.

The coating compositions of the present invention can additionallyinclude one or more other lubricious materials, such as non-polarpetroleum waxes, in lieu of or in addition to of those lubriciousmaterials discussed above. Non-limiting examples of non-polar petroleumwaxes include MICHEM® LUBE 296 microcrystalline wax, POLYMEKON® SPP-Wmicrocrystalline wax and PETROLITE 75 microcrystalline wax which arecommercially available from Michelman Inc. of Cincinnati, Ohio and BakerPetrolite, Polymer Division, of Cumming, Ga., respectively. Generally,the amount of this type of wax can be up to 10 weight percent of thetotal solids of the sizing composition.

The coating compositions of the present invention can also include aresin reactive diluent to further improve lubrication of the coatedfiber strands of the present invention and provide good processabilityin weaving and knitting by reducing the potential for fuzz, halos andbroken filaments during such manufacturing operations, while maintainingresin compatibility. As used herein, “resin reactive diluent” means thatthe diluent includes functional groups that are capable of chemicallyreacting with the same resin with which the coating composition iscompatible. The diluent can be any lubricant with one or more functionalgroups that react with a resin system, preferably functional groups thatreact with an epoxy resin system, and more preferably functional groupsthat react with an FR-4 epoxy resin system. Non-limiting examples ofsuitable lubricants include lubricants with amine groups, alcoholgroups, anhydride groups, acid groups or epoxy groups. A non-limitingexample of a lubricant with an amine group is a modified polyethyleneamine, e.g. EMERY 6717, which is a partially amidated polyethylene iminecommercially available from Cognis Corporation of Cincinnati, Ohio. Anon-limiting example of a lubricant with an alcohol group ispolyethylene glycol, e.g. CARBOWAX 300, which is a polyethylene glycolthat is commercially available from Union Carbide Corp. of Danbury,Conn. A non-limiting example of a lubricant with an acid group is fattyacids, e.g. stearic acid and salts of stearic acids. Non-limitingexamples of lubricants with an epoxy group include epoxidized soybeanoil and epoxidized linseed oil, e.g. FLEXOL LOE, which is an epoxidizedlinseed oil, and FLEXOL EPO, which is an epoxidized soybean oil, bothcommercially available from Union Carbide Corp. of Danbury, Conn., andLE-9300 epoxidized silicone emulsion, which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. Although not limitingin the present invention, the sizing composition can include a resinreactive diluent as discussed above in an amount up to 15 weight percentof the sizing composition on a total solids basis.

In another embodiment, the coating compositions of the present inventioncan comprise at least one anionic, nonionic or cationic surface activeagent. As used herein, “surface active agent” means any material whichtends to lower the solid surface tension or surface energy of the curedcomposition or coating. For purposes of the present invention, solidsurface tension can be measured according to the Owens-Wendt methodusing a Rame'-Hart Contact Angle Goniometer with distilled water andmethylene iodide as reagents.

The at least one surface active agent can be selected from amphiphilic,reactive functional group-containing polysiloxanes, amphiphilicfluoropolymers, polyacrylates and mixtures of any of the foregoing. Withreference to water-soluble or water-dispersible amphiphilic materials,the term “amphiphilic” means a polymer having a generally hydrophilicpolar end and a water-insoluble generally hydrophobic end. Nonlimitingexamples of suitable amphiphilic fluoropolymers includefluoroethylene-alkyl vinyl ether alternating copolymers (such as thosedescribed in U.S. Pat. No. 4,345,057) available from Asahi Glass Companyunder the tradename LUMIFLON; fluorosurfactants, fluoroaliphaticpolymeric esters commercially available from 3M of St. Paul, Minn. underthe tradename FLUORAD; functionalized perfluorinated materials, such as1H,1H-perfluoro-nonanol commercially available from FluoroChem USA; andperfluorinated (meth)acrylate resins. Other nonlimiting examples ofsuitable anionic surface active agents include sulfates or sulfonates.

Nonlimiting examples of suitable nonionic surface active agents includethose containing ether linkages and which are represented by thefollowing general formula: RO(R'O)_(n)H; wherein the substituent group Rrepresents a hydrocarbon group containing 6 to 60 carbon atoms, thesubstituent group R′ represents an alkylene group containing 2 or 3carbon atoms, and mixtures of any of the foregoing, and n is an integerranging from 2 to 100, inclusive of the recited values such as SURFYNOLnonionic polyoxyethylene surface active agents from Air ProductsChemicals, Inc.; PLURONIC or TETRONIC from BASF Corporation; TERGITOLfrom Union Carbide; and SURFONIC from Huntsman Corporation. Otherexamples of suitable nonionic surface active agents include blockcopolymers of ethylene oxide and propylene oxide based on a glycol suchas ethylene glycol or propylene glycol including those available fromBASF Corporation under the general trade designation PLURONIC.

Nonlimiting examples of suitable cationic surface active agents includeacid salts of alkyl amines; Imidazoline derivatives; ethoxylated aminesor amides, a cocoamine ethoxylate; ethoxylated fatty amines; andglyceryl esters.

Other examples of suitable surface active agents include homopolymersand copolymers of acrylate monomers, for example polybutylacrylate andcopolymers derived from acrylate monomers (such as ethyl (meth)acrylate,2-ethylhexylacrylate, butyl (meth)acrylate and isobutyl acrylate), andhydroxy ethyl(meth)acrylate and (meth)acrylic acid monomers.

The amount of surface active agent can range from 1 to 50 weight percentof the coating composition on a total solids basis.

The coating compositions can additionally include one or moreemulsifying agents for emulsifying or dispersing components of thecoating compositions, such as the particles 18 and/or lubriciousmaterials. Non-limiting examples of suitable emulsifying agents orsurfactants include polyoxyalkylene block copolymers (such as PLURONIC™F-108 polyoxypropylene-polyoxyethylene copolymer which is commerciallyavailable from BASF Corporation of Parsippany, New Jersey, (PLURONICF-108 copolymer is available in Europe under the tradename SYNPERONICF-108), ethoxylated alkyl phenyls (such as IGEPAL CA-630 ethoxylatedoctylphenoxyethanol which is commercially available from GAF Corporationof Wayne, New Jersey), polyoxyethylene octylphenyl glycol ethers,ethylene oxide derivatives of sorbitol esters (such as TMAZ 81 which iscommercially available BASF of Parsippany, New Jersey), polyoxyethylatedvegetable oils (such as ALKAMULS EL-719, which is commercially availablefrom Rhone-Poulenc/Rhodia), ethoxylated alkylphenyls (such as MACOLOP-10 SP which is also commercially available from BASF) and nonylphenylsurfactants (such as MACOL NP-6 and ICONOL NP-6 which are alsocommercially available from BASF, and SERMUL EN 668 which iscommercially available from CON BEA, Benelux). Generally, the amount ofemulsifying agent can range from 1 to 30 weight percent of the coatingcomposition on a total solids basis, preferably from 1 to 15 weightpercent.

Crosslinking materials, such as melamine formaldehyde, and plasticizers,such as phthalates, trimellitates and adipates, can also be included inthe coating compositions. The amount of crosslinker or plasticizer canrange from 1 to 5 weight percent of the coating composition on a totalsolids basis.

Other additives can be included in the coating compositions, such assilicones, fungicides, bactericides and anti-foaming materials,generally in an amount of less than 5 weight percent. Organic and/orinorganic acids or bases in an amount sufficient to provide the coatingcomposition with a pH of 2 to 10 can also be included in the coatingcomposition. A non-limiting example of a suitable silicone mulsion isLE-9300 epoxidized silicone emulsion, which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. An example of asuitable bactericide is BIOMET 66 antimicrobial compound, which iscommercially available from M & T Chemicals of Rahway, N.J. Suitableanti-foaming materials are the SAG materials, which are commerciallyavailable CK Witco Corporation of Greenwich, Conn. and MAZU DF-136,which is available from BASF Company of Parsippany, New Jersey. Ammoniumhydroxide can be added to the coating composition for coatingstabilization, if desired. Preferably, water, and more preferablydeionized water, is included in the coating composition in an amountsufficient to facilitate application of a generally uniform coating uponthe strand. The weight percentage of solids of the coating compositiongenerally ranges from 1 to 20 weight percent.

In one embodiment, the coating compositions of the present invention aresubstantially free of glass materials. As used herein, “substantiallyfree of glass materials” means that the coating compositions compriseless than 50 volume percent of glass matrix materials for forming glasscomposites, preferably less than 35 volume percent. In a more preferredembodiment, the coating compositions of the present invention areessentially free of glass materials. As used herein, “essentially freeof glass materials” means that the coating compositions comprise lessthan 20 volume percent of glass matrix materials for forming glasscomposites, preferably less than 5 volume percent, and more preferablyis free of glass materials. Examples of such glass matrix materialsinclude black glass ceramic matrix materials or aluminosilicate matrixmaterials such as are well known to those skilled in the art.

In one embodiment of the present invention, a fiber strand comprising aplurality of fibers is at least partially coated with a coatingcomprising an organic component and lamellar particles having a thermalconductivity of at least 1 Watt per meter K at a temperature of 300 K.In another embodiment, a fiber strand comprising a plurality of fibersis at least partially coated with a coating comprising an organiccomponent and non-hydratable, lamellar particles. In each of theseembodiments, the organic component and the lamellar particles can beselected from the coating components discussed above. The organiccomponent and the lamellar particles can be the same or different, andthe coating can be a residue of an aqueous coating composition or apowdered coating composition.

In yet another embodiment, a fiber strand comprising a plurality offibers is at least partially coated with a coating comprising at leastone boron-free lamellar particle having a thermal conductivity of atleast 1 Watt per meter K at a temperature of 300 K. In anotherembodiment, a fiber strand comprising a plurality of fibers is at leastpartially coated with a residue of an aqueous composition comprisinglamellar particles having a thermal conductivity of at least 1 Watt permeter K at a temperature of 300 K. In still another embodiment, a fiberstrand comprising a plurality of fibers is at least partially coatedwith a residue of an aqueous composition comprising alumina-free,non-hydratable particles having a thermal conductivity of at least 1Watt per meter K at a temperature of 300 K.

The components in these embodiments can be selected from the coatingcomponents discussed above, and additional components can also beselected from those recited above.

In another embodiment of the present invention, a fiber strandcomprising a plurality of fibers is at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising: (a) a plurality of discrete particles formed from materialsselected from non-heat expandable organic materials, inorganic polymericmaterials, non-heat expandable composite materials and mixtures thereof,the particles having an average particle size sufficient to allow strandwet out; (b) at least one lubricious material different from saidplurality of discrete particles; and (c) at least one film-formingmaterial. The components in these embodiments can be selected from thecoating components discussed above. In a further embodiment, theplurality of discrete particles provide an interstitial space betweenthe at least one of said fibers and at least one adjacent fiber.

In another embodiment, a fiber strand comprising a plurality of fibersis at least partially coated with a resin compatible coating compositionon at least a portion of a surface of at least one of said fibers, theresin compatible coating composition comprising: (a) a plurality ofparticles comprising (i) at least one particle formed from an organicmaterial; and (ii) at least one particle formed from an inorganicmaterial selected from boron nitride, graphite and metaldichalcogenides, wherein the plurality of particles have an averageparticle size sufficient to allow strand wet out; (b) at least onelubricious material different from said plurality of discrete particles;and (c) at least one film-forming material.

In yet another embodiment, a fiber strand comprising a plurality offibers is at least partially coated with a resin compatible coatingcomposition on at least a portion of a surface of at least one of saidfibers, the resin compatible coating composition comprising: (a) aplurality of discrete particles formed from materials selected fromorganic materials, inorganic polymeric materials, composite materialsand mixtures thereof, the particles having an average particle size,measured according to laser scattering techniques, ranging from 0.1 to 5micrometers; (b) at least one lubricious material different from saidplurality of discrete particles; and (c) at least one film-formingmaterial.

In a further embodiment, the resin compatible coating compositions setforth above contain (a) 20 to 60 weight percent of the plurality ofdiscrete particles on total solids basis, preferably 35 to 55 weightpercent, and more preferably 30 to 50 weight percent, (b) 0 to 80 weightpercent of the at least one lubricious material on a total solids basis,preferably from 1 to 50 weight percent, and more preferably from 20 to40 weight percent, and (c) 1 to 60 weight percent of the at least onefilm-forming material on total solids basis, preferably 5 to 50 weightpercent, and more preferably 10 to 30 weight percent.

In another embodiment of the present invention, a fiber strandcomprising a plurality of fibers is at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising: (a) a plurality of discrete, non-waxy particles formed frommaterials selected from organic materials, composite materials andmixtures thereof, the particles having an average particle size,measured according to laser scattering techniques, ranging from 0.1 to 5micrometers; and (b) at least one lubricious material different fromsaid plurality of discrete particles.

In still another embodiment of the present invention, a fiber strandcomprising a plurality of fibers is at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising greater than 20 weight percent on a total solids basis of atleast one particle selected from inorganic particles, organic hollowparticles and composite particles, the at least one particle having aMohs' hardness value which does not exceed the Mohs' hardness value ofat least one of said fibers.

In another embodiment of the present invention, a fiber strandcomprising a plurality of fibers is at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising (a) at least one lamellar, inorganic particles having a Mohs'hardness value which does not exceed the Mohs' hardness value of atleast one of said fibers; and (b) at least one polymeric material.

In an additional embodiment of the present invention, a fiber strandcomprising a plurality of fibers is at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising (a) at least one hollow, non-heat expandable organicparticle; and (b) at least one lubricious material different from the atleast one hollow organic particle.

The components in each of the foregoing embodiments can be selected fromthe coating components discussed above, and additional components canalso be selected from those recited above.

In one embodiment of the present invention, a fiber is coated with acomposition comprising an organic component and lamellar particleshaving a thermal conductivity of at least 1 Watt per meter K at atemperature of 300 K. In another embodiment, a fiber is coated with acomposition comprising an organic component and non-hydratable, lamellarparticles. In yet another embodiment, a fiber is coated with acomposition comprising at least one boron-free lamellar particle havinga thermal conductivity greater than 1 Watt per meter K at a temperatureof 300 K. In still another embodiment, a fiber is coated with acomposition comprising at least one lamellar particle having a thermalconductivity greater than 1 Watt per meter K at a temperature of 300 K.In yet another embodiment, a fiber is coated with a compositioncomprising at least one alumina-free, non-hydratable inorganic particlehaving a thermal conductivity greater than 1 Watt per meter K at atemperature of 300 K.

In another embodiment of the present invention, a fiber is coated with acomposition comprising (a) a plurality of discrete particles formed frommaterials selected from non-heat expandable organic materials, inorganicpolymeric materials, non-heat expandable composite materials andmixtures thereof, the particles having an average particle sizesufficient to allow strand wet out, (b) at least one lubricious materialdifferent from said plurality of discrete particles, and (c) at leastone film-forming material. In yet another embodiment, a fiber is coatedwith a composition comprising (a) a plurality of particles comprising(i) at least one particle formed from an organic material, and (ii) atleast one particle formed from an inorganic material selected from boronnitride, graphite and metal dichalcogenides, wherein the plurality ofparticles have an average particle size sufficient to allow strand wetout, (b) at least one lubricious material different from said pluralityof discrete particles, and (c) at least one film-forming material.

In still another embodiment, a fiber is coated with a compositioncomprising (a) a plurality of discrete particles formed from materialsselected from organic materials, inorganic polymeric materials,composite materials and mixtures thereof, the particles having anaverage particle size, measured according to laser scatteringtechniques, ranging from 0.1 to 5 micrometers, (b) at least onelubricious material different from said plurality of discrete particles,and (c) at least one film-forming material.

In another embodiment of the present invention, a fiber is coated with acomposition comprising (a) a plurality of discrete, non-waxy particlesformed from materials selected from organic materials, compositematerials and mixtures thereof, the particles having an average particlesize, measured according to laser scattering techniques, ranging from0.1 to 5 micrometers, and (b) at least one lubricious material differentfrom said plurality of discrete particles. In yet another embodiment, afiber is coated with a composition comprising a resin compatible coatingcomposition comprising at least one coating comprising greater than 20weight percent on a total solids basis of a plurality of particlesselected from inorganic particles, organic hollow particles andcomposite particles, said particles having a Mohs' hardness value whichdoes not exceed the Mohs' hardness value of said glass fiber.

In another embodiment of the present invention, a fiber is coated with acomposition comprising (a) a plurality of lamellar, inorganic particles,and (b) at least one polymeric material. In still another embodiment, afiber is coated with a composition comprising (a) a plurality of hollow,non-heat expandable organic particles, and (b) at least one polymericmaterial different from the at least one hollow organic particle. In anadditional embodiment, the present invention, a fiber is coated with aresin compatible coating composition having a primary coating of asizing composition on at least a portion of a surface of said fibers anda secondary coating comprising a residue of an aqueous coatingcomposition comprising a plurality of discrete particles applied over atleast a portion of the primary coating of the sizing composition.

The components in each of the foregoing embodiments can be selected fromthe coating components discussed above, and additional components canalso be selected from those recited above.

In one non-limiting embodiment of the present invention, at least aportion of at least one of said fibers of the fiber strand of thepresent invention has applied thereto an aqueous coating compositioncomprising POLARTHERM® 160 boron nitride powder and/or BORON NITRIDERELEASECOAT dispersion, EPON 826 epoxy film-forming material, PVP K-30polyvinyl pyrrolidone, A-187 epoxy-functional organo silane couplingagent, ALKAMULS EL-719 polyoxyethylated vegetable oil, IGEPAL CA-630ethoxylated octylphenoxyethanol, KESSCO PEG 600 polyethylene glycolmonolaurate ester which is commercially available from Stepan Company ofChicago, Ill. and EMERY® 6717 partially amidated polyethylene imine.

In another non-limiting embodiment of the present invention for weavingcloth, at least a portion of at least one of said glass fibers of thefiber strand of the present invention has applied thereto a driedresidue of an aqueous sizing composition comprising POLARTHERM® 160boron nitride powder and/or BORON NITRIDE RELEASECOAT dispersion,RD-847A polyester, PVP K-30 polyvinyl pyrrolidone, DESMOPHEN 2000polyester, A-174 acrylic-functional organo silane coupling agents andA-187 epoxy-functional organo silane coupling agents, PLURONIC F-108polyoxypropylene-polyoxyethylene copolymer, MACOL NP-6 nonylphenylsurfactant, VERSAMID 140 and LE-9300 epoxidized silicone emulsion.

In another non-limiting embodiment of a fabric for use in electroniccircuit boards of the present invention, at least a portion of at leastone of said glass fibers of the fiber strand of the present inventionhas applied thereto an aqueous coating composition comprisingPOLARTHERM® PT 160 boron nitride powder and/or ORPAC BORON NITRIDERELEASECOAT-CONC 25 dispersion, PVP K-30 polyvinyl pyrrolidone, A-174acryic-functional organo silane coupling agent, A-187 epoxy-functionalorgano silane coupling agent, ALKAMULS EL-719 polyoxyethylated vegetableoil, EMERY® 6717 partially amidated polyethylene imine, RD-847Apolyester, DESMOPHEN 2000 polyester, PLURONIC F-108polyoxypropylene-polyoxyethylene copolymer, ICONOL NP-6 alkoxylatednonyl phenyl and SAG 10 anti-foaming material. If desired, thisparticular embodiment can optional further include ROPAQUE® HP-1055and/or ROPAQUE® OP-96 styrene-acrylic copolymer hollow spheres.

In another non-limiting embodiment of fabric for use in electroniccircuit boards of the present invention, at least a portion of at leastone of said glass fibers of the fiber strand of the present inventionhas applied thereto a residue of an aqueous sizing compositioncomprising POLARTHERM® PT 160 boron nitride powder and/or ORPAC BORONNITRIDE RELEASECOAT-CONC 25 dispersion, RD-847A polyester, PVP K-30polyvinyl pyrrolidone, DESMOPHEN 2000 polyester, A-174acrylic-functional organo silane coupling agent, A-187 epoxy-functionalorgano silane coupling agent, PLURONIC F-108polyoxypropylene-polyoxyethylene copolymer, VERSAMID 140 polyamide, andMACOL NP-6 nonyl phenyl. If desired, this particular embodiment canoptional further include ROPAQUE® HP-1055 and/or ROPAQUE® OP-96styrene-acrylic copolymer hollow spheres.

In still another non-limiting embodiment for weaving fabric for use inlaminated printed circuit boards, at least a portion of at least one ofsaid glass fibers of the fiber strand of the present invention hasapplied thereto a residue of an aqueous primary coating compositioncomprising ROPAQUE® HP-1055 and/or ROPAQUE® OP-96 styrene-acryliccopolymer hollow spheres, PVP K-30 polyvinyl pyrrolidone, A-174acrylic-functional organo silane coupling agents and A-187epoxy-functional organo silane coupling agents, EMERY® 6717 partiallyamidated polyethylen imine, STEPANTEX 653 cetyl palmitate, TMAZ 81ethylene oxide derivatives of sorbitol esters, MACOL OP-10 ethoxylatedalkylphenyl and MAZU DF-136 anti-foaming material. Although notrequired, this particular embodiment preferably further includesPOLARTHERM® PT 160 boron nitride powder and/or ORPAC BORON NITRIDERELEASECOAT-CONC 25 dispersion.

In yet another non-limiting embodiment of fabric for use in electroniccircuit boards of the present invention, at least a portion of at leastone of said glass fibers of the fiber strand of the present inventionhas applied thereto a residue of an aqueous coating compositioncomprising DESMOPHEN 2000 polyester, A-174 acrylic-functional organosilane coupling agent, A-187 epoxy-functional organo silane couplingagent, PLURONIC F-108 polyoxypropylene-polyoxyethylene copolymer,VERSAMID 140 polyamide, MACOL NP-6 nonyl phenyl, POLYOX WSR 301poly(ethylene oxide) and DYNAKOLL Si 100 rosin. In addition, thisparticular embodiment further includes ROPAQUE® HP-1055 and/or ROPAQUE®OP-96 styrene-acrylic copolymer hollow spheres, and/or POLARTHERM® PT160 boron nitride powder and/or ORPAC BORON NITRIDE RELEASECOAT-CONC 25dispersion.

In another non-limiting embodiment of fabric for use in electroniccircuit boards of the present invention, at least a portion of at leastone of said glass fibers of the fiber strand of the present inventionhas applied thereto a residue of an aqueous coating compositioncomprising DESMOPHEN 2000 polyester, A-174 acrylic-functional organosilane coupling agent, A-187 epoxy-functional organo silane couplingagent, SYNPERONIC F-108 polyoxypropylene-polyoxyethylene copolymer,EUREDUR 140 polyamide, MACOL NP-6 nonyl phenyl, SERMUL EN 668ethoxylated nonylphenyl, POLYOX WSR 301 poly(ethylene oxide) andDYNAKOLL Si 100 rosin. In addition, this particular embodiment furtherincludes ROPAQUE® HP-1055 and/or ROPAQUE® OP-96 styrene-acryliccopolymer hollow spheres, and/or POLARTHERM® PT 160 boron nitride powderand/or ORPAC BORON NITRIDE RELEASECOAT-CONC 25 dispersion.

While not preferred, fiber strands having a residue of a coatingcomposition similar to those described above that are free of particles18 can be made in accordance with the present invention. In particular,it is contemplated that resin compatible coating compositions includingone or more film-forming materials, such as PVP K-30 polyvinylpyrrolidone; one or more silane coupling agents, such as A-174acrylic-functional organo silane coupling agents and A-187epoxy-functional organo silane coupling agents; and at least 25 percentby weight of the sizing composition on a total solids basis of alubricious material having polar characteristics, such as STEPANTEX 653cetyl palmitate, can be made in accordance with the present invention.It will be further appreciated by those skilled in the art that fiberstrands having a resin compatible coating composition that isessentially free of particles 18 can be woven into fabrics and made intoelectronic supports and electronic circuit boards (as described below)in accordance with the present invention.

The coating compositions of the present invention can be prepared by anysuitable method such as conventional mixing well known to those skilledin the art. Preferably, the components discussed above are diluted withwater to have the desired weight percent solids and mixed together. Theparticles 18 can be premixed with water, emulsified or otherwise addedto one or more components of the coating composition prior to mixingwith the remaining components of the coating.

Coating compositions according to the present invention can be appliedin many ways, for example by contacting the filaments with a roller orbelt applicator, spraying or other means. The coated fibers arepreferably dried at room temperature or at elevated temperatures. Thedryer removes excess moisture from the fibers and, if present, cures anycurable sizing composition components. The temperature and time fordrying the glass fibers will depend upon such variables as thepercentage of solids in the coating composition, components of thecoating composition and type of fiber.

As used herein, the term “cure” as used in connection with acomposition, e.g., “a cured composition,” shall mean that anycrosslinkable components of the composition are at least partiallycrosslinked. In certain embodiments of the present invention, thecrosslink density of the crosslinkable components, i.e., the degree ofcrosslinking, ranges from 5% to 100% of complete crosslinking. In otherembodiments, the crosslink density ranges from 35% to 85% of fullcrosslinking. In other embodiments, the crosslink density ranges from50% to 85% of full crosslinking. One skilled in the art will understandthat the presence and degree of crosslinking, i.e., the crosslinkdensity, can be determined by a variety of methods, such as dynamicmechanical thermal analysis (DMTA) using a Polymer Laboratories MK IIIDMTA analyzer conducted under nitrogen. This method determines the glasstransition temperature and crosslink density of free films of coatingsor polymers. These physical properties of a cured material are relatedto the structure of the crosslinked network.

According to this method, the length, width, and thickness of a sampleto be analyzed are first measured, the sample is tightly mounted to thePolymer Laboratories MK III apparatus, and the dimensional measurementsare entered into the apparatus. A thermal scan is run at a heating rateof 3° C./min, a frequency of 1 Hz, a strain of 120%, and a static forceof 0.01N, and sample measurements occur every two seconds. The mode ofdeformation, glass transition temperature, and crosslink density of thesample can be determined according to this method. Higher crosslinkdensity valves indicate a higher degree of crosslinking in the coating.

The amount of the coating composition present on the fiber strand ispreferably less than 30 percent by weight, more preferably less than 10percent by weight and most preferably between 0.1 to 5 percent by weightas measured by loss on ignition (LOI). The coating composition on thefiber strand can be a residue of an aqueous coating composition or apowdered coating composition. In one embodiment of the invention, theLOI is less than 1 percent by weight. As used herein, the term “loss onignition” means the weight percent of dried coating composition presenton the surface of the fiber strand as determined by Equation 1:LOI=100×[(W _(dry) −W _(bars))/W _(dry)]  (Eq. 1)wherein W_(dry) is the weight of the fiber strand plus the weight of thecoating composition after drying in an oven at 220° F. (about 104° C.)for 60 minutes and W_(bars) is the weight of the bare fiber strand afterheating the fiber strand in an oven at 1150° F. (about 621° C.) for 20minutes and cooling to room temperature in a dessicator.

After the application of a primary size, i.e., the initial size appliedafter fiber formation, the fibers are gathered into strands having 2 to15,000 fibers per strand, and preferably 100 to 1600 fibers per strand.

A secondary coating composition can be applied to the primary size in anamount effective to coat or impregnate the portion of the strands, forexample by dipping the coated strand in a bath containing the secondarycoating composition, spraying the secondary coating composition upon thecoated strand or by contacting the coated strand with an applicator asdiscussed above. The coated strand can be passed through a die to removeexcess coating composition from the strand and/or dried as discussedabove for a time sufficient to at least partially dry or cure thesecondary coating composition. The method and apparatus for applying thesecondary coating composition to the strand is determined in part by theconfiguration of the strand material. The strand is preferably driedafter application of the secondary coating composition in a manner wellknown in the art.

Suitable secondary coating compositions can include one or morefilm-forming materials, lubricants and other additives such as arediscussed above. The secondary coating is preferably different from theprimary sizing composition, i.e., it (1) contains at least one componentwhich is chemically different from the components of the sizingcomposition; or (2) contains at least one component in an amount whichis different from the amount of the same component contained in thesizing composition. Non-limiting examples of suitable secondary coatingcompositions including polyurethane are disclosed in U.S. Pat. Nos.4,762,750 and 4,762,751, which are specifically incorporated byreference herein.

Referring now to FIG. 2, in an alternative embodiment according to thepresent invention, the glass fibers 212 of the coated fiber strand 210can having applied thereto a primary layer 214 of a primary sizingcomposition which can include any of the sizing components in theamounts discussed above. Examples of suitable sizing compositions areset forth in Loewenstein at pages 237-291 (3d Ed. 1993) and U.S. Pat.Nos. 4,390,647 and 4,795,678, each of which is specifically incorporatedby reference herein. A secondary layer 215 of a secondary coatingcomposition is applied to at least a portion, and preferably over theentire outer surface, of the primary layer 214. The secondary coatingcomposition comprises one or more types of particles 216 such as arediscussed in detail above as particles 18. In one embodiment, thesecondary coating is a residue of an aqueous secondary coatingcomposition, and, in particular, a residue of an aqueous secondarycoating composition comprising lamellar particles on at least a portionof the primary coating. In another embodiment, the secondary coating isa powdered coating composition, and, in particular, a powdered coatingcomposition comprising lamellar particles on at least a portion of theprimary coating.

In an alternative embodiment, the particles of the secondary coatingcomposition comprise hydrophilic inorganic solid particles that absorband retain water in the interstices of the hydrophilic particles. Thehydrophilic inorganic solid particles can absorb water or swell when incontact with water or participate in a chemical reaction with the waterto form, for example, a viscous gel-like solution which blocks orinhibits further ingress of water into the interstices of atelecommunications cable which the coated glass fiber strand is used toreinforce. As used herein, “absorb” means that the water penetrates theinner structure or interstices of the hydrophilic material and issubstantially retained therein. See Hawley's Condensed ChemicalDictionary at page 3, which is specifically incorporated by referenceherein. “Swell” means that the hydrophilic particles expand in size orvolume. See Webster's New Collegiate Dictionary (1977) at page 1178,which is specifically incorporated by reference herein. Preferably, thehydrophilic particles swell after contact with water to at least one andone-half times their original dry weight, and more preferably two to sixtimes their original weight. Non-limiting examples of hydrophilicinorganic solid lubricant particles that swell include smectites such asvermiculite and montmorillonite, absorbent zeolites and inorganicabsorbent gels. Preferably, these hydrophilic particles are applied inpowder form over tacky sizing or other tacky secondary coatingmaterials.

In one embodiment of the present invention, a fiber strand comprising aplurality of fibers is at least partially coated with a resin compatiblecoating composition on at least a portion of a surface of the at leastone fiber, the resin compatible coating composition having a primarycoating of a sizing composition on at least a portion of a surface ofthe at least one fiber, and a secondary coating comprising a residue ofan aqueous coating composition comprising at least one discrete particleapplied over at least a portion of the primary coating of the sizingcomposition. In a preferred embodiment, the at least one discreteparticle is selected from a hydrophilic particle which absorbs andretains water in interstices of the hydrophilic particle.

Further to these embodiments, the amount of particles in the secondarycoating composition can range from 1 to 99 weight percent on a totalsolids basis, preferably from 20 to 90, more preferably from 25 to 80weight percent, and even more preferably from 50 to 60 weight percent.

In an alternative embodiment shown in FIG. 3, a tertiary layer 320 of atertiary coating composition can be applied to at least a portion of thesurface, and preferably over the entire surface, of a secondary layer315, i.e., such a fiber strand 312 would have a layer 314 of a primarysizing, a secondary layer 315 of a secondary coating composition and atertiary, outer layer 320 of the tertiary coating. The tertiary coatingof the coated fiber strand 310 is preferably different from the primarysizing composition and the secondary coating composition, i.e., thetertiary coating composition (1) contains at least one component whichis chemically different from the components of the primary sizing andsecondary coating composition; or (2) contains at least one component inan amount which is different from the amount of the same componentcontained in the primary sizing or secondary coating composition.

In this embodiment, the secondary coating composition comprises one ormore polymeric materials discussed above, such as polyurethane, and thetertiary powdered coating composition comprises solid particles, such asthe POLARTHERM® boron nitride particles, and hollow particles, such asROPAQUE® pigments, which are discussed above. Preferably, the powderedcoating is applied by passing the strand having a liquid secondarycoating composition applied thereto through a fluidized bed or spraydevice to adhere the powder particles to the tacky secondary coatingcomposition. Alternatively, the strands can be assembled into a fabric912 before the layer of tertiary coating 920 is applied, as shown inFIG. 9. Composite or laminate 910, which combines fabric 912 with aresin 914, also includes an electrically conductive layer 922, similarto the construction shown in FIG. 8 which will be discussed later ingreater detail. The weight percent of powdered solid particles adheredto the coated fiber strand 310 can range from 0.1 to 75 weight percentof the total weight of the dried strand, and preferably 0.1 to 30 weightpercent.

The tertiary powdered coating can also include one or more polymericmaterials such as are discussed above, such as acrylic polymers,epoxies, or polyolefins, conventional stabilizers and other modifiersknown in the art of such coatings, preferably in dry powder form.

In one embodiment, a fiber strand comprising a plurality of fibers is atleast partially coated with a primary coating of a sizing compositionapplied to at least a portion of a surface of the at least one fiber, asecondary coating composition comprising a polymeric material applied toat least a portion of the primary composition, and a tertiary coatingcomposition comprising discrete particles applied to at least a portionof the secondary coating. In another embodiment, a fiber strandcomprising a plurality of fibers is at least partially coated with aprimary coating of a sizing composition applied to at least a portion ofa surface of at least one of said fibers, a secondary coatingcomposition comprising a polymeric material applied to at least aportion of the primary composition, and a tertiary coating compositioncomprising lamellar particles applied to at least a portion of thesecondary coating.

In one preferred embodiment, at least one of the coatings in each of theforegoing embodiments is different. In another preferred embodiment, atleast two of the coatings in each of the foregoing embodiments are thesame. Additionally, the tertiary coating can be a residue of an aqueousemulsion or a powdered coating composition. The coating compositionscomprise one or more coating components discussed above.

The various embodiments of the coated fiber strands discussed above canbe used as continuous strand or further processed into diverse productssuch as chopped strand, twisted strand, roving and/or fabric, such aswovens, nonwovens (including but not limited to unidirectional, biaxialand triaxial fabrics), knits, mats (both chopped and continuous strandmats) and multilayered fabrics (i.e. overlaying layers of fabric heldtogether by stitching or some other material to form a three-dimensionalfabric structure). In addition, the coated fiber strands used as warpand weft (i.e. fill) strands of a fabric can be non-twisted (alsoreferred to as untwisted or zero twist) or twisted prior to weaving andthe fabric can include various combinations of both twisted andnon-twisted warp and weft strands.

Preferred embodiments of the present invention include an at leastpartially coated fabric comprising at least one of the fiber strandscomprising a plurality of fibers discussed in detail above. Thus, an atleast partially coated fabric made from each of the disclosed fiberstrands comprising a plurality of fibers is, therefore, contemplated inthe present invention. For example, one preferred embodiment of thepresent invention is directed to an at least partially coated fabriccomprising at least one strand comprising plurality of fibers, thecoating comprising an organic component and lamellar particles having athermal conductivity of at least 1 Watt per meter K at a temperature of300 K.

In one embodiment of the present invention, the coating compositionsaccording to the present invention are applied to an individual fiber.In another embodiment, the coating is applied to at least one fiberstrand. In another embodiment, the coating composition according to thepresent invention is applied to the fabric. These alternativeembodiments are fully discussed below.

Although the prior discussion is generally directed toward applying thecoating composition of the present invention directly on glass fibersafter fiber forming and subsequently incorporating the fibers into afabric, the present invention also includes embodiments wherein thecoating composition of the present invention is applied to a fabric. Thecoating composition can be applied to a fabric, for example, by applyingthe coating to a fiber strand before the fabric is manufactured, or byapplying the coating to the fabric after it has been manufactured usingvarious techniques well known in the art. Depending on the processing ofthe fabric, the coating composition of the present invention can beapplied either directly to the glass fibers in the fabric or to anothercoating already on the glass fibers and/or fabric. For example, theglass fibers can be coated with a conventional starch-oil sizing afterforming and woven into a fabric. The fabric can then be treated toremove starch-oil sizing prior to applying the coating composition ofthe present invention. This sizing removal can be accomplished usingtechniques well known in the art, such as thermal treatment or washingof the fabric. In this instance, the coating composition would directlycoat the surface of the fibers of the fabric. If any portion of thesizing composition initially applied to the glass fibers after formingis not removed, the coating composition of the present invention wouldthen be applied over the remaining portion of the sizing compositionrather than directly to the fiber surface.

In another embodiment of the present invention, selected components ofthe coating composition of the present invention can be applied to theglass fibers immediately after forming and the remaining components ofthe coating composition can be applied to the fabric after it is made.In a manner similar to that discussed above, some or all of the selectedcomponents can be removed from the glass fibers prior to coating thefibers and fabric with the remaining components. As a result, theremaining components will either directly coat the surface of the fibersof the fabric or coat those selected components that were not removedfrom the fiber surface.

In another preferred embodiment according to the present invention, afabric comprising at least one strand comprising a plurality of fibersis at least partially coated with a primary coating and a secondarycoating on at least a portion of the primary coating, the secondarycoating comprising particles of an inorganic material having a thermalconductivity greater than 1 Watts per meter K at a temperature of 300 K.

In another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers is at least partially coated withcoating comprising (a) lamellar, inorganic particles having a Mohs'hardness value which does not exceed the Mohs' hardness value of the atleast one glass fiber, and (b) a film-forming material.

In yet another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers is at least partially coated with acoating comprising (a) metallic particles having a Mohs' hardness valuewhich does not exceed the Mohs' hardness value of the at least one glassfiber, the metallic particles being selected from indium, thallium, tin,copper, zinc, gold and silver, and (b) a film-forming material.

In another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers is at least partially coated with aprimary coating and a secondary coating on at least a portion of theprimary coating, the secondary coating comprising a plurality ofhydrophilic particles which absorb and retain water in the intersticesof the hydrophilic particles.

In still another embodiment of the present invention, a fabriccomprising at least one strand comprising a plurality of fibers has aresin compatible coating composition on at least a portion of a surfaceof the fabric, the resin compatible coating composition comprising (a) aplurality of discrete particles formed from materials selected fromorganic materials, inorganic polymeric materials, composite materialsand mixtures thereof, the particles having an average particle size,measured according to laser scattering, ranging from 0.1 to 5micrometers, (b) at least one lubricious material different from saidplurality of discrete particles, and (c) at least one film-formingmaterial.

In another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers has a resin compatible coatingcomposition on at least a portion of a surface of the fabric, the resincompatible coating composition comprising (a) a plurality of discrete,non-waxy particles formed from materials selected from organicmaterials, composite materials and mixtures thereof, and at least onelubricious material different from said plurality of discrete particles.

In another embodiment of the present invention, a fabric comprising atleast one strand comprising a plurality of fibers has a resin compatiblecoating composition on at least a portion of a surface of the fabric,the resin compatible coating composition comprising (a) a plurality ofhollow organic particles, and (b) at least one polymeric materialdifferent from the hollow organic particles.

Another embodiment of present invention is directed to a fabriccomprising at least one strand comprising a plurality of fibers, whereinat least a portion of the fabric has a resin compatible coating with aloss on ignition of ranging from 0.1 to 1.6, and an air permeability,measured according to ASTM D 737, of no greater than 10 standard cubicfeet per minute per square foot.

As used herein, “air permeability” means how permeable the fabric is toflow of air therethrough. Air permeability can be measured by ASTM D 737Standard Test Method for Air Permeability of Textile Fabrics, which isspecifically incorporated by reference herein.

These components used in these various embodiments can be selected fromthe coating components discussed above, and additional components canalso be selected from those recited above.

In a preferred embodiment of the present invention, a fabric adapted toreinforce an electronic support is made by a method comprising the stepsof:

-   -   (a) obtaining at least one fill yarn comprising a plurality of        fibers and having a first resin compatible coating on at least a        portion of the at least one fill yarn;    -   (b) obtaining at least one warp yarn comprising a plurality of        fibers and having a second resin compatible coating on at least        a portion of the at least one warp yarn; and    -   (c) weaving the at least one fill yarn and the at least one warp        yarn having a loss on ignition of less than 2.5 percent by        weight to form a fabric adapted to reinforce an electronic        support.

In an additional embodiment of the present invention, a fabric isassembled by (a) slidingly contacting at least a portion of a firstglass fiber strand comprising a plurality of glass fibers having on atleast a portion of surfaces thereof a coating according to any of theprevious embodiments, either individually or in combination, whichinhibit abrasive wear of the surfaces of the plurality of glass fibers,in sliding contact with surface asperities of a portion of a fabricassembly device, the surface asperities having a Mohs' hardness valuewhich is greater than a Mohs' hardness value of glass fibers of thefirst glass fiber strand; and (b) interweaving the first glass fiberstrand with a second fiber strand to form a fabric.

Further embodiments of the present invention are directed to methods forinhibiting abrasive wear of a fiber strand comprising at least one glassfiber by sliding contact with surface asperities of a solid objectcomprising:

-   -   (a) applying a coating composition according to any of the        previous embodiments, either individually or in combination, to        at least a portion of a surface of at least one glass fiber of a        glass fiber strand;    -   (b) at least partially drying the composition to form a sized        glass fiber strand having a residue of the composition upon at        least a portion of the surface of the at least one glass fiber;        and    -   (c) sliding at least a portion of the glass fiber strand to        contact surface asperities of a solid object, the surface        asperities having a hardness value which is greater than a        hardness value of the at least one glass fiber, such that        abrasive wear of the at least one glass fiber of the glass fiber        strand by contact with the surface asperities of the solid        object is inhibited by the coating composition.

As above, the components of the coatings used in these embodiments canbe selected from the coating components discussed above, and additionalcomponents can also be selected from those recited above.

The coated fiber strands 10, 210, 310 and products formed therefrom,such as the coated fabrics recited above, can be used in a wide varietyof applications, but are preferably used as reinforcements 410 forreinforcing polymeric matrix materials 412 to form a composite 414, suchas is shown in FIG. 4, which will be discussed in detail below. Suchapplications include but are not limited to laminates for printedcircuit boards, reinforcements for telecommunications cables, andvarious other composites.

The coated strands and fabrics of the present invention are preferablycompatible with typical polymeric matrix resins used to make electronicsupports and printed circuit boards. In addition, the coated fiberstrands are suitable for use on air-jet looms, which are commonly usedto make the reinforcing fabrics for such applications. Conventionalsizing compositions applied to fibers to be woven using air-jet loomsinclude components such as starches and oils that are generally notcompatible with such resin systems. It has been observed that weavingcharacteristics of fiber strands coated with a coating compositioncomprising particles 18 in accordance with the present inventionapproximate the weaving characteristics of fiber strands coated withconventional starch/oil based sizing compositions and are compatiblewith FR-4 epoxy resins. Although not meant to be bound by any particulartheory, it is believed that the particles 18 of the instant inventionfunction in a manner similar to the starch component of conventionalstarch/oil sizing compositions during processing and air-jet weaving byproviding the necessary fiber separation and air drag for the air jetweaving operation but function in a manner different from theconventional compositions by providing compatibility with the epoxyresin system. For example, the particles 18 contribute a dry, powdercharacteristic to the coating similar to the dry lubricantcharacteristics of a starch coating.

In the coated strands of the present invention, the particles canadvantageously provide interstices between the fibers of the strandwhich facilitate flow of the matrix materials therebetween to morequickly and/or uniformly wet-out and wet-through the fibers of thestrand. Additionally, the strands preferably have high strand openness(discussed above) which also facilitates flow of the matrix materialinto the bundles. Surprisingly, in certain embodiments, the amount ofparticles can exceed 20 weight percent of the total solids of thecoating composition applied to the fibers, yet still be adequatelyadhered to the fibers and provide strands having handlingcharacteristics at least comparable to strands without the particlecoating.

Referring now to FIG. 8, one advantage of the coated strands of thepresent invention is that laminates 810 made from fabrics 812incorporating the coated strands can have good coupling at the interfacebetween the fabric 812 and the polymeric matrix material 814. Goodinterfacial coupling can provide for good hydrolytic stability andresistance to metal migration (previously discussed) in electronicsupports 818 made from laminates 810.

In another non-limiting embodiment shown in FIG. 5, coated fiber strands510 made according to the present invention can be used as warp and/orweft strands 514, and 516 in a knit or woven fabric 512 reinforcement,preferably to form a laminate for a printed circuit board (shown inFIGS. 7-9). Although not required, the warp strands 514 can be twistedprior to use by any conventional twisting technique known to thoseskilled in the art. One such technique uses twist frames to impart twistto the strand at 0.5 to 3 turns per inch. The reinforcing fabric 512 canpreferably include 5 to 100 warp strands 514 per centimeter (about 13 to254 warp strand per inch) and preferably has 6 to 50 weft strands percentimeter (about 15 to about 127 weft strands per inch). The weaveconstruction can be a regular plain weave or mesh (shown in FIG. 5),although any other weaving style well known to those skilled in the art,such as a twill weave or satin weave, can be used.

In one embodiment, a suitable woven reinforcing fabric 512 of thepresent invention can be formed by using any conventional loom wellknown to those skilled in the art, such as a shuttle loom, air jet loomor rapier loom, but preferably is formed using an air jet loom.Preferred air jet looms are commercially available from Tsudakoma ofJapan as Model Nos. 103, 1031 1033 or ZAX; Sulzer Ruti Model Nos.L-5000, L-5100 or L-5200 which are commercially available from SulzerBrothers LTD. of Zurich, Switzerland; and Toyoda Model No. JAT610.

As set forth in the figures, air jet weaving refers to a type of fabricweaving using an air jet loom 626 (shown in FIG. 6) in which the fillyarn (weft) 610 is inserted into the warp shed by a blast of compressedair 614 from one or more air jet nozzles 618 (shown in FIGS. 6 and 6 a),as discussed above. The fill yarn 610 is propelled across the width 624of the fabric 628 (about 10 to about 60 inches), and more preferably0.91 meters (about 36 inches) by the compressed air.

The air jet filling system can have a single, main nozzle 616, butpreferably also has a plurality of supplementary, relay nozzles 620along the warp shed 612 for providing blasts of supplementary air 622 tothe fill yarn 610 to maintain the desired air pressure as the yarn 610traverses the width 624 of the fabric 628. The air pressure (gauge)supplied to the main air nozzle 616 preferably ranges from 103 to 413kiloPascals (kPa) (about 15 to about 60 pounds per square inch (psi)),and more preferably is 310 kPa (about 45 psi). The preferred style ofmain air nozzle 616 is a Sulzer Ruti needle air jet nozzle unit ModelNo. 044 455 001 which has an internal air jet chamber having a diameter617 of 2 millimeters and a nozzle exit tube 619 having a length 621 of20 centimeters (commercially available from Sulzer Ruti of Spartanburg,North Carolina). Preferably, the air jet filling system has 15 to 20supplementary air nozzles 620 which supply auxiliary blasts of air inthe direction of travel of the fill yarn 610 to assist in propelling theyarn 610 across the loom 626. The air pressure (gauge) supplied to eachsupplementary air nozzle 620 preferably ranges from 3 to 6 bars.

The fill yarn 610 is drawn from the supply package 630 by a feedingsystem 632 at a feed rate of 180 to 550 meters per minute, andpreferably 274 meters (about 300 yards) per minute. The fill yarn 610 isfed into the main nozzle 618 through a lamp. A blast of air propels apredetermined length of yarn (approximately equal to the desired widthof the fabric) through the confusor guide. When the insertion iscompleted, the end of the yarn distal to the main nozzle 618 is cut by acutter 634.

The compatibility and aerodynamic properties of different yarns with theair jet weaving process can be determined by the following method, whichwill generally be referred to herein as the “Air Jet Transport DragForce” Test Method. The Air Jet Transport Drag Force Test is used tomeasure the attractive or pulling force (“drag force”) exerted upon theyarn as the yarn is pulled into the air jet nozzle by the force of theair jet. In this method, each yarn sample is fed at a rate of 274 meters(about 300 yards) per minute through a Sulzer Ruti needle air jet nozzleunit Model No. 044 455 001 which has an internal air jet chamber havinga diameter 617 of 2 millimeters and a nozzle exit tube 619 having alength 621 of 20 centimeters (commercially available from Sulzer Ruti ofSpartanburg, North Carolina) at an air pressure of 310 kiloPascals(about 45 pounds per square inch) gauge. A tensiometer is positioned incontact with the yarn at a position prior to the yarn entering the airjet nozzle. The tensiometer provides a measurement of the gram force(drag force) exerted upon the yarn by the air jet as the yarn is pulledinto the air jet nozzle.

The drag force per unit mass can be used as a basis for relativecomparison of yarn samples. For relative comparison, the drag forcemeasurements are normalized over a one centimeter length of yarn. TheGram Mass of a one centimeter length of yarn can be determined accordingto Equation 2:Gram Mass=(π(d/2)²) (N) (ρ_(glass)) (1 centimeter length of yarn) (Eq.2)where d is the diameter of a single fiber of the yarn bundle, N is thenumber of fibers in the yarn bundle and ρ_(glass) is the density of theglass at a temperature of 25° C. (about 2.6 grams per cubic centimeter).Table C lists the diameters and number of fibers in a yarn for severaltypical glass fiber yarn products.

TABLE C Fiber Diameter Number of Yarn type (centimeters) Fibers inBundle G75 9 × 10⁻⁴ 400 G150 9 × 10⁻⁴ 200 E225 7 × 10⁻⁴ 200 D450 5.72 ×10⁻⁴   200

For example, the Gram Mass of a one centimeter length of G75 yarn is(π(9×10⁻⁴/2)²) (400) (2.6 grams per cubic centimeter) (1 centimeterlength of yarn)=6.62×10⁻⁴ gram mass. For D450 yarn, the Gram Mass is1.34×10⁻⁴ gram mass. The relative drag force per unit mass (“Air JetTransport Drag Force”) is calculated by dividing the drag forcemeasurement (gram force) determined by the tensiometer by the Gram Massfor the type of yarn tested. For example, for a sample of G75 yarn, ifthe tensiometer measurement of the drag force is 68.5, then the Air JetTransport Drag Force is equal to 68.5 divided by 6.62×10⁻⁴=103,474 gramforce per gram mass of yarn.

The Air Jet Transport Drag Force of the yarn used to form a woven fabricfor a laminate according to the present invention, determined accordingto the Air Jet Transport Drag Force Test Method discussed above, ispreferably greater than 100,000 gram force per gram mass of yarn, morepreferably ranges from 100,000 to 400,000 gram force per gram mass ofyarn, and even more preferably ranges from 120,000 to 300,000 gram forceper gram mass of yarn.

The fabric of the present invention is preferably woven in a style whichis suitable for use in a laminate for an electronic support or printedcircuit board, such as are disclosed in “Fabrics Around the World”, atechnical bulletin of Clark-Schwebel, Inc. of Anderson, South Carolina(1995), which is specifically incorporated by reference herein. Thelaminates can be a unidirectional laminate wherein most of the fibers,yarns or strands in each layer of fabric are oriented in the samedirection.

For example, a non-limiting fabric style using E225 E-glass fiber yarnsis Style 2116, which has 118 warp yarns and 114 fill (or weft) yarns per5 centimeters (60 warp yarns and 58 fill yarns per inch); uses 7 22 1×0(E225 1/0) warp and fill yarns; has a nominal fabric thickness of 0.094millimeters (about 0.037 inches); and a fabric weight (or basis weight)of 103.8 grams per square meter (about 3.06 ounces per square yard). Anon-limiting example of a fabric style using G75 E-glass fiber yarns isStyle 7628, which has 87 warp yarns and 61 fill yarns per 5 centimeters(44 warp yarns and 31 fill yarns per inch); uses 9 68 1×0 (G75 1/0) warpand fill yarns; has a nominal fabric thickness of 0.173 millimeters(about 0.0068 inches); and a fabric weight of 203.4 grams per squaremeter (about 6.00 ounces per square yard). A non-limiting example of afabric style using D450 E-glass fiber yarns is Style 1080, which has 118warp yarns and 93 fill yarns per 5 centimeters (60 warp yarns and 47fill yarns per inch); uses 5 11 1×0 (D450 1/0) warp and fill yarns; hasa nominal fabric thickness of 0.053 millimeters (about 0.0021 inches);and a fabric weight of 46.8 grams per square meter (about 1.38 ouncesper square yard). A non-limiting example of a fabric style using D900E-glass fiber yarns is Style 106, which has 110 warp yarns and 110 fillyarns per 5 centimeters (56 warp yarns and 56 fill yarns per inch); uses5 5.5 1×0 (D900 1/0) warp and fill yarns; has a nominal fabric thicknessof 0.033 millimeters (about 0.013 inches); and a fabric weight of 24.4grams per square meter (about 0.72 ounces per square yard). Anothernon-limiting example of a fabric style using D900 E-glass fiber yarns isStyle 108, which has 118 warp yarns and 93 fill yarns per 5 centimeters(60 warp yarns and 47 fill yarns per inch); uses 5 5.5 1×2 (D900 1/2)warp and fill yarns; has a nominal fabric thickness of 0.061 millimeters(about 0.0024 inches); and a fabric weight of 47.5 grams per squaremeter (about 1.40 ounces per square yard). A non-limiting example of afabric style using both E225 and D450 E-glass fiber yarns is Style 2113,which has 118 warp yarns and 110 fill yarns per 5 centimeters (60 warpyarns and 56 fill yarns per inch); uses 7 22 1×0 (E225 1/0) warp yarnand 5 11 1×0 (D450 1/0) fill yarn; has a nominal fabric thickness of0.079 millimeters (about 0.0031 inches); and a fabric weight of 78.0grams per square meter (about 2.30 ounces per square yard). Anon-limiting example of a fabric style using both G50 and G75 E-glassfiber yarns is Style 7535 which has 87 warp yarns and 57 fill yarns per5 centimeters (44 warp yarns and 29 fill yarns per inch); uses 9 68 1×0(G75 1/0) warp yarn and 9 99 1×0 (G50 1/0) fill yarn; has a nominalfabric thickness of 0.201 millimeters (about 0.0079 inches); and afabric weight of 232.3 grams per square meter (about 6.85 ounces persquare yard).

These and other useful fabric style specification are given inIPC-EG-140 “Specification for Finished Fabric Woven from ‘E’ Glass forPrinted Boards”, a publication of The Institute for Interconnecting andPackaging Electronic Circuits (June 1997), which is specificallyincorporated by reference herein. Although the aforementioned fabricstyles use twisted yarns, it is contemplated that these or other fabricstyles using zero-twist yarns or rovings in conjunction with or in lieuof twisted yarns can be made in accordance with the present invention.

In an embodiment of the present invention, some or all of the warp yarnin the fabric can have fibers coated with a first resin compatiblesizing composition and some or all of the fill yarn can have fiberscoated with a second resin compatible coating differing from the firstcomposition, i.e., the second composition (1) contains at least onecomponent which is chemically different or differs in form from thecomponents of the first sizing composition; or (2) contains at least onecomponent in an amount which is different from the amount of the samecomponent contained in the first sizing composition.

Referring now to FIG. 7, the fabric 712 can be used to form a compositeor laminate 714 by coating and/or impregnating with a matrix material,preferably a polymeric film-forming thermoplastic or thermosettingmatrix material 716. The composite or laminate 714 is suitable for useas an electronic support. As used herein, “electronic support” means astructure that mechanically supports and/or electrically interconnectselements. Examples include, but are not limited to, active electroniccomponents, passive electronic components, printed circuits, integratedcircuits, semiconductor devices and other hardware associated with suchelements including but not limited to connectors, sockets, retainingclips and heat sinks.

Preferred embodiments of the present invention are directed to areinforced composite comprising at least one partial coated fiber strandcomprising a plurality of fibers discussed in detail above. Reinforcedcomposites made from each of the disclosed fiber strands comprising aplurality of fibers are therefore contemplated by the present invention.For example, one preferred embodiment of the present invention isdirected to a reinforced composite comprising a matrix material and atleast one partially coated fiber strand comprising a plurality offibers, the coating comprising an organic component and lamellarparticles having a thermal conductivity of at least 1 Watt per meter Kat a temperature of 300 K.

Another preferred embodiment of the present invention is directed to areinforced composite comprising (a) an at least partially coated fiberstrand comprising a plurality of fibers, the coating comprising at leastone lamellar particle, and (b) a matrix material.

Yet another preferred embodiment is directed to a reinforced compositecomprising (a) an at least partially coated fiber strand comprising aplurality of glass fibers, the coating comprising a residue of anaqueous composition comprising (i) a plurality of discrete particlesformed from materials selected from organic materials, inorganicpolymeric materials, composite materials and mixtures thereof; (ii) atleast one lubricious material different from said plurality of discreteparticles; and (iii) at least one film-forming material; and (b) amatrix material.

Still another preferred embodiment of the present invention is directedto a reinforced composite comprising at least one fiber strand and amatrix material, wherein the reinforced composite further comprises aresidue of an aqueous composition comprising (a) a plurality of discreteparticles formed from materials selected from organic materials,inorganic polymeric materials, composite materials and mixtures thereof;(b) at least one lubricious material different from said plurality ofdiscrete particles; and (c) at least one film-forming material.

Another preferred embodiment of the present invention is directed to areinforced composite comprising (a) an at least partially coated fiberstrand comprising a plurality of glass fibers, the coating comprising aresidue of an aqueous u composition comprising greater than 20 weightpercent on a total solids basis of discrete particles which have a Mohs'hardness value which does not exceed a Mohs' hardness value of at leastone of said glass fibers; and (b) a matrix material.

Another preferred embodiment is directed to a reinforced compositecomprising at least one fiber strand comprising a plurality of glassfibers and a matrix material, wherein the reinforced composite furthercomprises a residue of an aqueous composition comprising greater than 20weight percent on a total solids basis of discrete particles which havea Mohs' hardness value which does not exceed a Mohs' hardness value ofat least one of said glass fibers.

An additional embodiment of the present invention is directed to areinforced composite comprising (a) at least one fiber strand comprisinga plurality of glass fibers, the strand coated with a resin compatiblecomposition comprising a plurality of discrete particles formed frommaterials selected from organic materials, inorganic polymericmaterials, composite materials and mixtures thereof, wherein thediscrete particles have an average particle size less than 5micrometers; and (b) a matrix material. In particular, the plurality ofdiscrete particles are formed from materials selected from non-heatexpandable organic materials, inorganic polymeric materials, non-heatexpandable composite materials, and mixtures of any of the foregoing.

The components of the coatings and resin compatible compositions used inthe foregoing embodiments directed to reinforced composites can beselected from the coating components discussed above, and additionalcomponents can also be selected from those recited above.

Preferred matrix materials useful in the present invention includethermosetting materials such as thermosetting polyesters, vinyl esters;epoxides (containing at least one epoxy or oxirane group in themolecule, such as polyglycidyl ethers of polyhydric alcohols or thiols),phenylics, aminoplasts, thermosetting polyurethanes, derivatives of anyof the foregoing, and mixtures of any of the foregoing. Preferred matrixmaterials for forming laminates for printed circuit boards are FR-4epoxy resins, which are polyfunctional epoxy resins such as difunctionalbrominated epoxy resins, polyimides and liquid crystalline polymers, thecompositions of which are well know to those skilled in the art. Iffurther information regarding such compositions is needed, seeElectronic Materials Handbook™, ASM International (1989) at pages534-537, which is specifically incorporated by reference herein.

Non-limiting examples of suitable polymeric thermoplastic matrixmaterials include polyolefins, polyamides, thermoplastic polyurethanesand thermoplastic polyesters, vinyl polymers, and mixtures of any of theforegoing. Further examples of useful thermoplastic materials includepolyimides, polyether sulfones, polyphenyl sulfones, polyetherketones,polyphenylene oxides, polyphenylene sulfides, polyacetals, polyvinylchlorides and polycarbonates.

A preferred matrix material formulation consists of EPON 1120-A80 epoxyresin (commercially available from Shell Chemical Company of Houston,Tex.), dicyandiamide, 2-methylimidazole and DOWANOL PM glycol ether(commercially available from The Dow Chemical Co. of Midland, Mich.).

Other components which can be included with the polymeric matrixmaterial and reinforcing material in the composite include colorants orpigments, lubricants or processing aids, ultraviolet light (UV)stabilizers, antioxidants, other fillers and extenders. In a preferredembodiment, inorganic materials are included with the polymeric matrixmaterial. These inorganic materials include ceramic materials andmetallic materials, and can be selected from the inorganic materialsdescribed in detail above.

The fabric 712 can be coated and impregnated by dipping the fabric 712in a bath of the polymeric matrix material 716, for example, asdiscussed in R. Tummala (Ed.), Microelectronics Packaging Handbook,(1989) at pages 895-896, which are specifically incorporated byreference herein. More generally, chopped or continuous fiber strandreinforcing material can be dispersed in the matrix material by hand orany suitable automated feed or mixing device which distributes thereinforcing material generally evenly throughout the polymeric matrixmaterial. For example, the reinforcing material can be dispersed in thepolymeric matrix material by dry blending all of the componentsconcurrently or sequentially.

The polymeric matrix material 716 and strand can be formed into acomposite or laminate 714 by a variety of methods which are dependentupon such factors as the type of polymeric matrix material used. Forexample, for a thermosetting matrix material, the composite can beformed by compression or injection molding, pultrusion, filamentwinding, hand lay-up, spray-up or by sheet molding or bulk moldingfollowed by compression or injection molding. Thermosetting polymericmatrix materials can be cured by the inclusion of crosslinkers in thematrix material and/or by the application of heat, for example. Suitablecrosslinkers useful to crosslink the polymeric matrix material arediscussed above. The temperature and curing time for the thermosettingpolymeric matrix material depends upon such factors such as, but notlimited to, the type of polymeric matrix material used, other additivesin the matrix system and thickness of the composite.

For a thermoplastic matrix material, suitable methods for forming thecomposite include direct molding or extrusion compounding followed byinjection molding. Methods and apparatus for forming the composite bythe above methods are discussed in 1. Rubin, Handbook of PlasticMaterials and Technology (1990) at pages 955-1062, 1179-1215 and1225-1271, which are specifically incorporated by reference herein.

Additional preferred embodiments of the present invention are directedto reinforced laminates adapted for an electronic support comprising anat least partially coated fabric comprising at least one fiber stranddiscussed in detail above. Thus, reinforced laminate adapted for anelectronic support made from each of the disclosed fabrics comprising atleast one fiber strand are therefore contemplated by the presentinvention. For example, one preferred embodiment of the presentinvention is directed to a reinforced laminate adapted for an electronicsupport comprising a matrix material and an at least one partiallycoated fabric comprising at least one fiber strand, the coatingcomprising an organic component and lamellar particles having a thermalconductivity of at least 1 Watt per meter K at a temperature of 300 K.In a further embodiment, the coating is compatible with the matrixmaterial in the reinforced laminate adapted for an electronic support.

An additional embodiment of the present invention is directed to areinforced laminate adapted for an electronic support, the laminatecomprising (a) a matrix material, and at least one non-degreased fabriccomprising at least one fiber strand, at least a portion of the at leastone fabric having a coating which is compatible with the matrix materialin said reinforced laminate adapted for said electronic support. Anotherembodiment of the present invention is directed to a reinforced laminateadapted for an electronic support, the laminate comprising (a) a matrixmaterial, and (b) at least one fabric comprising at least one fiberstrand and having a non-finishing resin compatible coating compositionon at least a portion of a surface of the fabric.

As used herein, a “non-degreased fabric” is a fabric that has notundergone a conventional fiber process removing non-resin compatiblesizing materials from the fabric. As discussed above, heat cleaning andwaterjet washing, in addition to scrubbing are examples of suchconventional fiber processes. As used herein, a “non-finishing” resincompatible coating composition refers to the resin compatible coatingcompositions discussed above that are not used in conventional fiberfinishing processes. For example, a non-finishing resin compatiblecoating composition refers to the primary, secondary and/or tertiarycoating composition discussed above, but does not refer to typicalfinishing sizes made, for example, from a silane coupling agent andwater, and applied to the fiber after degreasing. The present invention,however, does contemplate a coating comprising a resin compatiblecoating according to the present invention with a finishing size appliedto the coating.

Another preferred embodiment of the present invention is directed to amethod of forming a laminate for use in an electronic supportapplication, the method comprising the steps of:

-   -   (a) obtaining a fabric adapted to reinforce an electronic        support formed by weaving at least one fill yarn comprising a        plurality of fibers and having a first resin compatible coating        on at least a portion of the at least one fill yarn and at least        one warp yarn comprising a plurality of fibers and having a        second resin compatible coating on at least a portion of the at        least one warp yarn;    -   (b) at least partially coating at least a portion of the fabric        with a matrix material resin;    -   (c) at least partially curing the at least partially coated        fabric to form a prepreg layer; and    -   (d) laminating two or more prepreg layers together to form a        laminate adapted for use in the electronic support.

The components of the coatings used in the foregoing embodimentsdirected to reinforced laminates can be selected from the coatingcomponents discussed above, and additional components can also beselected from those recited above.

Additional preferred embodiments of the present invention are directedto prepregs for an electronic support comprising an at least partiallycoated fabric comprising at least one fiber strand discussed in detailabove. Thus, prepregs for an electronic support made from each of thedisclosed fabrics comprising at least one fiber strand are thereforecontemplated by the present invention.

Another embodiment of the present invention is directed a prepreg for anelectronic support, the prepreg comprising (a) a matrix material, and atleast one non-degreased fabric comprising at least one fiber strand, atleast a portion of the at least one fabric having a coating which iscompatible with the matrix material in said prepreg for said electronicsupport. Yet another embodiment of the present invention is directed toa prepreg for an electronic support, the prepreg comprising (a) a matrixmaterial, and (b) at least one fabric comprising at least one fiberstrand and having a non-finishing resin compatible coating compositionon at least a portion of a surface of the fabric.

As above, the components of the coatings used in the foregoingembodiments can be selected from the coating components discussed above,and additional components can also be selected from those recited above.

In a particular non-limiting embodiment of the invention shown in FIG.8, composite or laminate 810 includes fabric 812 impregnated with acompatible matrix material 814. The impregnated fabric can then besqueezed between a set of metering rolls to leave a measured amount ofmatrix material, and dried to form an electronic support in the form ofa semicured substrate or prepreg. An electrically conductive layer 820can be positioned along a portion of a side 822 of the prepreg in amanner to be discussed below in the specification, and the prepreg iscured to form an electronic support 818 with an electrically conductivelayer. In another embodiment of the invention, and more typically in theelectronic support industry, two or more prepregs are combined with oneor more electrically conductive layers and laminated together and curedin a manner well known to those skilled in the art, to form amultilayered electronic support. For example, but not limiting thepresent invention, the prepreg stack can be laminated by pressing thestack, e.g. between polished steel plates, at elevated temperatures andpressures for a predetermined length of time to cure the polymericmatrix and form a laminate of a desired thickness. A portion of one ormore of the prepregs can be provided with an electrically conductivelayer either prior to or after lamination and curing such that theresulting electronic support is a laminate having at least oneelectrically conductive layer along a portion of an exposed surface(hereinafter referred to as a “clad laminate”).

Circuits can then be formed from the electrically conductive layer(s) ofthe single layer or multilayered electronic support using techniqueswell known in the art to construct an electronic support in the form ofa printed circuit board or printed wiring board (hereinaftercollectively referred to as “electronic circuit boards”).

Additional preferred embodiments of the present invention are directedto electronic supports and electronic circuit boards comprising an atleast partially coated fabric comprising at least one fiber stranddiscussed in detail above. Thus, electronic supports and electroniccircuit boards made from each of the disclosed fabrics comprising atleast one fiber strand are therefore contemplated by the presentinvention.

Another embodiment of the present invention is directed to an electronicsupport comprising (a) at least one non-degreased fabric comprising atleast one fiber strand, at least a portion of the at least onenon-degreased fabric having a coating which is compatible with a matrixmaterial; and (b) at least one matrix material on at least a portion ofthe at least one fabric in the electronic support. An additionalembodiment is directed to an electronic support comprising (a) at leastone fabric comprising at least one fiber strand and having anon-finishing resin compatible coating composition on at least a portionof a surface of the fabric; and (b) at least one matrix material on atleast a portion of the at least one fabric in the electronic support.

Yet another embodiment of the present invention is directed to a methodof forming an electronic support, the method comprising the steps of:

-   -   (a) obtaining a fabric adapted to reinforce an electronic        support formed by weaving at least one fill yarn comprising a        plurality of fibers and having a first resin compatible coating        an at least a portion of the at least one fill yarn and at least        one warp yarn comprising a plurality of fibers and having a        second resin compatible coating on at least a portion of the at        least one warp yarn;    -   (b) at least partially coating at least a portion of the fabric        with a matrix material resin;    -   (c) at least partially curing the coating into the at least a        portion of the fabric to form a prepreg layer; and    -   (d) laminating one or more prepreg layers together with one or        more electrically conductive layers to form the electronic        support.

In a further preferred embodiment, the at least one fabric and the atleast one matrix form a first composite layer in the electronic support.In another further preferred embodiment, the electronic support furthercomprises a second composite layer different from the first compositelayer.

An additional preferred embodiment is directed to an electronic circuitboard comprising (a) an electronic support comprising (i) at least onenon-degreased fabric comprising at least one fiber strand, at least aportion of the at least one non-degreased fabric having a coating whichis compatible with a matrix material, ad (ii) at least one matrixmaterial on at least a portion of the at least one fabric in theelectronic support; and (b) an electronically conductive layer, thesupport and the conductive layer being contained in the electroniccircuit board.

An additional embodiment is directed to an electronic circuit boardcomprising (a) an electronic support comprising (i) at least one fabriccomprising at least one fiber strand and having a non-finishing resincompatible coating composition on at least a portion of a surface of thefabric; and (ii) at least one matrix material on at least a portion ofthe at least one fabric in the electronic support; and (b) anelectronically conductive layer, the support and the conductive layerbeing contained in the electronic circuit board.

In a further preferred embodiment, the electrically conductive layer ispositioned adjacent to a selected portion of the electronic support. Inanother further preferred embodiment, the at least one fabric and the atleast one matrix form a first composite layer. In another embodiment,the electronic support further comprises a second composite layerdifferent from the first composite layer. Preferably, the electricallyconductive layer is positioned adjacent to a selected portion of thefirst and/or second composite layers electronic support.

Another embodiment of the present invention is directed to a method offorming a printed circuit board, the method comprising the steps of;

-   -   (a) obtaining an electronic support comprising one or more        electrically conductive layers and at least one fabric adapted        to reinforce the electronic support formed by weaving at least        one fill yarn comprising a plurality of fibers and having a        first resin compatible coating on at least a portion of the at        least one fill yarn and at least one warp yarn comprising a        plurality of glass and having a second resin compatible coating        on at least a portion of the at least one warp yarn; and    -   (b) patterning at least one of the one or more electrically        conductive layers of the electronic support to form a printed        circuit board.

The components of the coatings used in the foregoing embodimentsdirected to electronic supports and electronic circuit boards can beselected from the coating components discussed above, and additionalcomponents can also be selected from those recited above.

If desired, apertures or holes (also referred to as “vias”) can beformed in the electronic supports, to allow for electricalinterconnection between circuits and/or components on opposing surfacesof the electronic support, by any convenient manner known in the art,including but not limited to mechanical drilling and laser drilling.More specifically, referring to FIG. 10, an aperture 1060 extendsthrough at least one layer 1062 of fabric 1012 of an electronic support1054 of the present invention. The fabric 1012 comprises coated fiberstrands comprising a plurality of glass fibers having a layer that iscompatible with a variety of polymeric matrix materials as taughtherein. In forming the aperture 1060, electronic support 1054 ispositioned in registry with an aperture forming apparatus, such as adrill bit 1064 or laser tip. The aperture 1060 is formed through aportion 1066 of the at least one layer 1062 of fabric 1012 by drillingusing the drill 1064 or laser.

In a preferred embodiment, the laminate has a deviation distance afterdrilling 2000 holes through a stack of 3 laminates at a hole density of62 holes per square centimeter (400 holes per square inch) and a chipload of 0.001 with a 0.46 mm (0.018 inch) diameter tungsten carbidedrill of no greater than 36 micrometers. In an additional embodiment,the laminate has a drill tool % wear after drilling 2000 holes through astack of 3 laminates at a hole density of 62 holes per square centimeter(400 holes per square inch) and a chip load of 0.001 with a 0.46 mm(0.018 inch) diameter tungsten carbide drill of no greater than 32percent.

In further embodiment, a fluid stream comprising an inorganic lubricantis dispensed proximate to the aperture forming apparatus such that theinorganic lubricant contacts at least a portion of an interface betweenthe aperture forming apparatus and the electronic support. Preferably,the inorganic lubricant is selected from the inorganic lubricantdescribed in detail above.

Another embodiment of the present invention, is directed to a method forforming an aperture through a layer of fabric of an electronic systemsupport for an electronic circuit board comprising:

-   -   (1) positioning an electronic system support comprising a        portion of a layer of fabric comprising a coated fiber strand        comprising a resin compatible coating composition on at least a        portion of a surface of the fabric, in which an aperture is to        be formed in registry with an aperture forming apparatus; and    -   (2) forming an aperture in the portion of the layer of fabric.

After formation of the apertures, a layer of electrically conductivematerial is deposited on the walls of the aperture or the aperture isfilled with an electrically conductive material to facilitate therequired electrical interconnection between one or more electricallyconductive layers (not shown in FIG. 10) on the surface of theelectronic support 1054 and/or heat dissipation. The vias can extendpartially through or entirely through the electronic support and/orprinted circuit board, they can be exposed at one or both surfaces ofthe electronic support and/or printed circuit board or they can becompleted buried or contained within the electronic support and/orcircuit board (“buried via”).

The electrically conductive layer 820 shown in FIG. 8 can be formed byany method well known to those skilled in the art. For example, but notlimiting the present invention, the electrically conductive layer can beformed by laminating a thin sheet or foil of metallic material onto atleast a portion of a side of the semi-cured or cured prepreg orlaminate. As an alternative, the electrically conductive layer can beformed by depositing a layer of metallic material onto at least aportion of a side of the semi-cured or cured prepreg or laminate usingwell known techniques including but not limited to electrolytic plating,electroless plating or sputtering. Metallic materials suitable for useas an electrically conductive layer include but are not limited tocopper (which is preferred), silver, aluminum, gold, tin, tin-leadalloys, palladium and combinations thereof.

In another non-limiting embodiment of the present invention, theelectronic support can be in the form of a multilayered electroniccircuit board constructed by laminating together one or more electroniccircuit boards (described above) with one or more clad laminates(described above) and/or one or more prepregs (described above). Ifdesired, additional electrically conductive layers can be incorporatedinto the electronic support, for example along a portion of an exposedside of the multilayered electronic circuit board. Furthermore, ifrequired, additional circuits can be formed from the electricallyconductive layers in a manner discussed above. It should be appreciatedthat depending on the relative positions of the layers of themultilayered electronic circuit board, the board can have both internaland external circuits. Additional apertures are formed, as discussedearlier, partially through or completely through the board to allowelectrical interconnection between the layers at selected locations. Itshould be appreciated that the resulting structure can have someapertures that extend completely through the structure, some aperturesthat extend only partially through the structure, and some aperturesthat are completely within the structure.

Preferably, the thickness of the laminate forming the electronic support254 is greater than 0.051 mm (about 0.002 inches), and more preferablyranges from 0.13 mm (about 0.005 inches) to 2.5 mm (about 0.1 inches).For an eight ply laminate of 7628 style fabric, the thickness isgenerally 1.32 mm (about 0.052 inches). The number of layers of fabricin a laminate can vary based upon the desired thickness of the laminate.

The resin content of the laminate can preferably range from 35 to 80weight percent, and more preferably 40 to 75 weight percent. The amountof fabric in the laminate can preferably range from 20 to 65 weightpercent and more preferably ranges from 25 to 60 weight percent.

For a laminate formed from woven E-glass fabric and using an FR-4 epoxyresin matrix material having a minimum glass transition temperature of110° C., the preferred minimum flexural strength in the cross machine orwidth direction (generally perpendicular to the longitudinal axis of thefabric, i.e., in the fill direction) is greater than. 3×10⁷ kg/m², morepreferably greater than 3.52×10⁷ kg/m² (about 50 kpsi), and even morepreferably greater than 4.9×10⁷ kg/m² (about 70 kpsi) according toIPC-4101 “Specification for Base Materials for Rigid and MultilayerPrinted Boards” at page 29, a publication of The Institute forInterconnecting and Packaging Electronic Circuits (December 1997).IPC-4101 is specifically incorporated by reference herein in itsentirety. In the length direction, the desired minimum flexural strengthin the length direction (generally parallel to the longitudinal axis ofthe fabric, i.e., in the warp direction) is preferably greater than4×10⁷ kg/m², and more preferably greater than 4.23×10⁷ kg/m². Theflexural strength is measured according to ASTM D-790 and IPC-TM-650Test Methods Manual of the Institute for Interconnecting and PackagingElectronics (December 1994) (which are specifically incorporated byreference herein) with metal cladding completely removed by etchingaccording to section 3.8.2.4 of IPC-4101. Advantages of the electronicsupports of the present invention include high flexural strength(tensile and compressive strength) and high modulus, which can lessendeformation of a circuit board including the laminate.

Electronic supports of the present invention in the form of copper cladFR-4 epoxy laminates preferably have a coefficient of thermal expansionfrom 50° C. to 288° C. in the z-direction of the laminate (“Z-CTE”),i.e., across the thickness of the laminate, of less than 5.5 percent,and more preferably ranging from 0.01 to 5.0 weight percent, accordingto IPC Test Method 2.4.41 (which is specifically incorporated byreference herein). Each such laminate preferably contains eight layersof 7628 style fabric, although styles such as, but not limited to, 106,108, 1080, 2113, 2116 or 7535 style fabrics can alternatively be used.In addition, the laminate can incorporate combinations of these fabricstyles. Laminates having low coefficients of thermal expansion aregenerally less susceptible to expansion and contraction and can minimizeboard distortion.

The instant invention further contemplates the fabrication ofmultilayered laminates and electronic circuit boards which include atleast one composite layer made according to the teachings herein and atleast one composite layer made in a manner different from the compositelayer taught herein, e.g. made using conventional glass fiber compositetechnology. More specifically and as is well known to those skilled inthe art, traditionally the filaments in continuous glass fiber strandsused in weaving fabric are treated with a starch/oil sizing whichincludes partially or fully dextrinized starch or amylose, hydrogenatedvegetable oil, a cationic wetting agent, emulsifying agent and water,including but not limited to those disclosed in Loewenstein at pages237-244 (3d Ed. 1993), which is specifically incorporated by referenceherein. Warp yarns produced from these strands are thereafter treatedwith a solution prior to weaving to protect the strands against abrasionduring the weaving process, e.g. poly(vinyl alcohol) as disclosed inU.S. Pat. No. 4,530,876 at column 3, line 67 through column 4, line 11,which is specifically incorporated by reference herein. This operationis commonly referred to as slashing. The poly(vinyl alcohol) as well asthe starch/oil size are generally not compatible with the polymericmatrix material used by composite manufacturers and the fabric is thuscleaned to remove essentially all organic material from the surface ofthe glass fibers prior to impregnating the woven fabric. This can beaccomplished In a variety ways, for example by scrubbing the fabric or,more commonly, by heat treating the fabric in a manner well known in theart. As a result of the cleaning operation, there is no suitableinterface between the polymeric matrix material used to impregnate thefabric and the cleaned glass fiber surface, so that a coupling agentmust be applied to the glass fiber surface. This operation is sometimereferred to by those skilled in the art as finishing. The couplingagents most commonly used in finishing operations are silanes, includingbut not limited to those disclosed in E. P. Plueddemann, Silane CouplingAgents (1982) at pages 146-147, which is specifically incorporated byreference herein. Also see Loewenstein at pages 249-256 (3d Ed. 1993).After treatment with the silane, the fabric is impregnated with acompatible polymeric matrix material, squeezed between a set of meteringrolls and dried to form a semicured prepreg as discussed above. Itshould be appreciated that in the present invention depending on thenature of the sizing, the cleaning operation and/or the matrix resinused in the composite, the slashing and/or finishing steps can beeliminated. One or more prepregs incorporating conventional glass fibercomposite technology can then be combined with one or more prepregsincorporating the instant invention to form an electronic support asdiscussed above, and in particular a multilayered laminate or electroniccircuit board. For more information regarding fabrication of electroniccircuit boards, see Electronic Materials Handbook™, ASM International(1989) at pages 113-115, R. Tummala (Ed.), Microelectronics PackagingHandbook, (0.1989) at pages 858-861 and 895-909, M. W. Jawitz, PrintedCircuit Board Handbook (1997) at pages 9.1-9.42, and C. F. Coombs, Jr.(Ed.), Printed Circuits Handbook, (3d Ed. 1988), pages 6.1-6.7, whichare specifically incorporated by reference herein.

The composites and laminates forming the electronic supports of theinstant invention can be used to form packaging used in the electronicsindustry, and more particularly first, second and/or third levelpackaging, such as that disclosed in Tummala at pages 25-43, which isspecifically incorporated by reference herein. In addition, the presentinvention can also be used for other packaging levels.

The present invention, in one non-limiting embodiment, the flexuralstrength of an unclad laminate, made in accordance with the presentinvention from 8 layers or plies of prepreg formed from a Style 7628,E-glass fabric and an FR-4 polymeric resin having a T_(g) of 140° C. andtested according to IPC-TM-650, No. 2.4.4 (which is specificallyincorporated by reference herein), is preferably greater than 100,000pounds per square inch (about 690 megaPascals) when tested parallel tothe warp direction of the fabric and preferably greater than 80,000(about 552 megapascals) when tested parallel to the fill direction ofthe fabric.

In another non-limiting embodiment of the present invention, the shortbeam shear strength of an unclad laminate, made in accordance with thepresent invention from 8 layers or plies of prepreg formed from a Style7628, E-glass fabric and an FR-4 polymeric resin having a T_(g) of 140°C. and tested according to ASTM D 2344-84 (which is specificallyincorporated by reference herein) using a span length to thickness ratioof 5, is preferably greater than 7400 pounds per square inch (about 51megaPascals) when tested parallel to the warp direction of the fabricand preferably greater than 5600 pounds per square inch (about 39megaPascals) when tested parallel to the fill direction of the fabric.

In another non-limiting embodiment of the present invention, the shortbeam shear strength of an unclad laminate, made in accordance with thepresent invention from 8 layers or plies of prepreg formed from a Style7628, E-glass fabric and an FR-4 polymeric resin having a T_(g) of 140°C. and tested according to ASTM D 2344-84 using a span length tothickness ratio of 5 and after being immersed in boiling water for 24hours, is preferably greater than 5000 pounds per square inch (about 34megaPascals) when tested parallel to the warp direction of the fabricand preferably greater than 4200 pounds per square inch (about 30megapascals) when tested parallel to the fill direction of the fabric.

The present invention also includes a method for reinforcing a matrixmaterial to form a composite. The method comprises: (1) applying to afiber strand reinforcing material at least one primary, secondary and/ortertiary coating composition discussed in detail above comprisingparticles which provide interstitial spaces between adjacent fibers ofthe strand, (2) drying the coating to form a coating upon thereinforcing material; (3) combining the reinforcing material with thematrix material; and (4) at least partially curing the matrix materialto provide a reinforced composite. Although not limiting the presentinvention, the reinforcing material can be combined with the polymericmatrix material, for example by dispersing it in the matrix material.Preferably, the coating or coatings form a substantially uniform coatingupon the reinforcing material upon drying. In one non-limitingembodiment of the present invention, the particles comprise at least 20weight percent of the sizing composition on a total solids basis. Inanother non-limiting embodiment, the particles have a minimum averageparticle dimension of at least 3 micrometers, and preferably at least 5micrometers. In a further non-limiting embodiment, the particles have aMohs' hardness value that is less than a Mohs' hardness value of anyglass fibers that are contained in the fiber strand.

The present invention also includes a method for inhibiting adhesionbetween adjacent fibers of a fiber strand, comprising the steps of: (1)applying to a fiber strand at least one primary, secondary and/ortertiary coating composition discussed in detail above includingparticles which provide interstitial spaces between adjacent fibers ofthe strand; (2) drying the coating to form a coating upon the fibers ofthe fiber strand, such that adhesion between adjacent fibers of thestrand is inhibited. Preferably, the coating or coatings form asubstantially uniform coating upon the reinforcing material upon drying.In one non-limiting embodiment of the present invention, the particlescomprise at least 20 weight percent of the sizing composition on a totalsolids basis. In another non-limiting embodiment, the particles have aminimum average particle dimension of at least 3 micrometers, andpreferably at least 5 micrometers. In a spherical particle, for example,the minimum average particle dimension will correspond to the diameterof the particle. In a rectangularly shaped particle, for example, theminimum average particle dimension will refer to the average length,width or height of the particle. In a further non-limiting embodiment,the particles have a Mohs' hardness value that is less than a Mohs'hardness value of any glass fibers that are contained in the fiberstrand.

The present invention also includes a method for inhibiting hydrolysisof a matrix material of a fiber-reinforced composite. The methodcomprises: (1) applying to a fiber strand reinforcing material at leastone primary, secondary and/or tertiary coating composition discussed indetail above comprising greater than 20 weight percent on a total solidsbasis of discrete particles; (2) drying the coating to form coating uponthe reinforcing material; (3) combining the reinforcing material withthe matrix material; and (4) at least partially curing the matrixmaterial to provide a reinforced composite. Preferably, the coating orcoatings form a substantially uniform coating upon the reinforcingmaterial upon drying. As discussed above, the reinforcing material canbe combined with the matrix material, for example, by dispersing thereinforcing material in the matrix material.

In one, non-limiting embodiment of the present invention, the fabric ispreferably woven into a Style 7628 fabric and has an air permeability ofless then 10 cubic feet per minute and more preferably less than 5 cubicfeet per minute, as measured by ASTM D 737 Standard Test Method for AirPermeability of Textile Fabrics. Although not limiting in the presentinvention, it is believed that the elongated cross-section and highstrand openness of the warp yarns of the present invention (discussed indetail below) reduces the air permeability of the fabrics of the presentinvention as compared to more conventional fabrics made using slashedwarp yarns.

As previously discussed, in conventional weaving operations forelectronic support applications, the warp yarns are typically coatedwith a slashing size prior to weaving to help prevent abrasion of thewarp yarns during the weaving process. The slashing size composition istypically applied to the warp yarns by passing the warp yarns through adip pan or bath containing the slashing size and then through one ormore sets of squeeze rolls to remove any excess material. Typicalslashing size compositions can include, for example, film formingmaterials, plasticizers and lubricants. A film-forming material commonlyused in slashing size compositions is polyvinyl alcohol. After slashing,the warp yarns are dried and wound onto a loom beam. The number andspacing of the warp yarn ends depends on the style of the fabric to bewoven. After drying, the slashed warp yarns will typically have a losson ignition of greater than 2.0 percent due to the combination of theprimary and slashing sizes.

Typically, the slashing sizing, as well as the starch/oil size aregenerally not compatible with the polymeric resin material used bycomposite manufacturers when incorporating the fabric as reinforcementfor an electronic support so that the fabric must be cleaned to removeessentially all organic material from the surface of the glass fibersprior to impregnating the woven fabric. This can be accomplished in avariety ways, for example by scrubbing the fabric or, more commonly, byheat treating the fabric in a manner well known in the art. As a resultof the cleaning operation, there is no suitable interface between thepolymeric matrix material used to impregnate the fabric and the cleanedglass fiber surface, so that a coupling agent must be applied to theglass fiber surface. This operation is sometime referred to by thoseskilled in the art as finishing. Typically, the finishing size providesthe fabric with an LOI less than 0.1%.

After treatment with the finishing size, the fabric is impregnated witha compatible polymeric matrix material, squeezed between a set ofmetering rolls and dried to form a semicured prepreg as discussed above.For more information regarding fabrication of electronic circuit boards,see Electronic Materials Handbook™, ASM International (1989) at pages113-115, R. Tummala (Ed.); Microelectronics Packaging Handbook, (1989)at pages 858-861 and 895-909; M. W. Jawitz, Printed Circuit BoardHandbook (1997) at pages 9.1-9.42; and C. F. Coombs, Jr. (Ed.), PrintedCircuits Handbook, (3d Ed. 1988), pages 6.1-6.7, which are specificallyincorporated by reference herein.

Since the slashing process puts a relatively thick coating on the warpyarns, the yarns become rigid and inflexible as compared to unslashedwarp yarns. The slashing size tends to hold the yarn together in a tightbundle having a generally circular cross-section. Although not meant tobe limiting in the present invention, it is believed that such a yarnstructure (i.e., tight bundles and generally circular cross-sections)can hinder the penetration of polymeric resin materials into the warpyarn bundle during subsequent processing steps, such aspre-impregnation, even after the removal of the slashing size.

Although slashing is not detrimental to the present invention, slashingis not preferred. Therefore, in a preferred embodiment of the presentinvention, the warp yarns are not subjected to a slashing step prior toweaving and are substantially free of slashing size residue. As usedherein, the term substantially free” means that the warp yarns have lessthan 20 percent by weight, more preferably less than 5 percent by weightof slashing size residue in a more preferred embodiment of the presentinvention, the warp yarns are not subjected to a slashing step prior toweaving and are essentially free of slashing size residue. As usedherein, the term “essentially free” means that the warp yarns have lessthan 0.5 percent by weight, more preferably less than 0.1 percent byweight and most preferably 0 percent by weight of a residue of aslashing size on the surfaces thereof. However, if the warp yarns aresubjected to a secondary coating operation prior to weaving, preferably,the amount of the secondary coating applied to the surface of the warpyarns prior to weaving is less than 0.7 percent by weight of the sizedwarp yarn.

In one preferred embodiment of the present invention, the loss onignition of the warp yarns is preferably less than 2.5 percent byweight, more preferably less than 1.5 percent by weight and mostpreferably less than 0.8 percent during weaving. In addition, the fabricof the present invention preferably has an overall loss on ignitionranging form 0.1 to 1.6 percent, more preferably ranging from 0.4 to 1.3percent, and even more preferably between 0.6 to 1 percent.

In another, non-limiting embodiment of the present invention, the warpyarn preferably has an elongated cross-section and high strand openness.As used herein, the term “elongated cross-section” means that the warpyarn has a generally flat or ovular cross-sectional shape. High strandopenness, discussed above, refers to the characteristic that theindividual fibers of the yarn or strand are not tightly held togetherand open spaces exist between one or more of the individual fibersfacilitating penetration of a matrix material into the bundle. Slashedwarp yarns (as discussed above) generally have a circular cross-sectionand low strand openness and thus do not facilitate such penetration.Although not limiting in the present invention, it is believed that goodresin penetration into the warp yarn bundles (i.e., good resin wet-out)during lamination can improve the overall hydrolytic stability oflaminates and electronic supports made in accordance with the presentinvention, by reducing or eliminating paths of ingress for moisture intothe laminates and electronic supports. This can also have a positiveeffect in reducing the tendency of printed circuit boards made from suchlaminates and electronic supports to exhibit electrical short failuresdue to the formation of conductive anodic filaments when exposed, underbias, to humid conditions.

The degree of strand openness can be measured by an F-index test. In theF-index test, the yarn to be measured is passed over a series ofvertically aligned rollers and is positioned adjacent to a horizontallydisposed sensing device comprising a light emitting surface and anopposing light sensing surface, such that a vertical axis of the yarn isin generally parallel alignment with the light emitting and lightsensing surfaces. The sensing device is mounted at a vertical heightthat positions it about half-way between the vertically aligned rollersand the horizontal distance between the yarn and the sensing device iscontrolled by moving the rollers toward or away from the sensing device.As the yarn passes over the rollers (typically at about 30 meters perminute), depending on the openness of the strand, one or more portionsof the yarn can eclipse a portion of the light emanating from theemitting surface thereby triggering a response in the light sensingsurface. The number of eclipses are then tabulated for a given length ofyarn (typically about 10 meters) and the resulting ratio (i.e., numberof eclipses per unit length) is considered to be a measure of strandopenness.

It is believed that the tight warp yarn structure of fabric woven fromconventional, slashed glass fiber yarns as well as the low openness ofsuch yarns as discussed above, results in these conventional fabricshaving an air permeability that is higher than the air permeability ofthe preferred fabrics of the present invention, which preferably includean elongated warp yarn cross-section and higher warp yarn openness. Inone, non-limiting embodiment of the present invention, the fabric has anair permeability, as measured by ASTM D 737 Standard Test Method, of nogreater than 10 standard cubic feet per minute per square foot (about0.05 standard cubic meters per minute per square meter), more preferablyno greater than 5 cubic feet per minute per square foot (1.52 standardcubic meters per minute per square meter), and most preferably nogreater than 3 cubic feet per minute per square foot (0.91 standardcubic meters per minute per square meter). In another embodiment of theinvention, the fabric is woven into a 7628 style fabric and has an airpermeability, as measured by ASTM D 737 Standard Test Method. of nogreater than 10 standard cubic feet per minute per square foot, morepreferably no greater than 5 cubic feet per minute per square foot, andmost preferably no greater than 3 cubic feet per minute per square foot.

Although not meant to be bound or in any way limited by any particulartheory, it is postulated that warp yarns having elongated or flatcross-sections can also lend to improved drilling performance inlaminates made from fabrics incorporating the warp yarns. Moreparticularly, since the cross over points between the warp and fillyarns in fabrics having warp yarns with elongated cross-sections willhave a lower profile than conventional fabrics incorporating warp yarnshaving circular cross-sections, a drill bit drilling through the fabricwill contact fewer glass fibers during drilling and thereby be subjectedto less abrasive wear.

As previously discussed, in one embodiment of the present invention,preferably both the warp yarns and the fill yarns have a resincompatible primary coating composition applied thereto during forming.The resin compatible primary coating composition applied to the warpyarn can be the same as the resin compatible primary coating compositionapplied to the fill yarn or it can be different from the resincompatible primary coating composition applied to the fill yarn. As usedherein, the phrase “different from the resin compatible primary coatingcomposition applied to the fill yarn” in reference to the resincompatible primary coating composition applied to the warp yarn meansthat at least one component of the primary coating composition appliedto the warp yarn is present in an amount different from that componentin the primary coating composition applied to the fill yarn or that atleast one component present in the primary coating composition appliedto the warp yarn is not present in the primary coating compositionapplied to the fill yarn or that at least one component present in theprimary coating composition applied to the fill yarn is not present inthe primary coating composition applied to the warp yarn.

In still another, non-limiting embodiment of the present invention, theglass fibers of the yarns of the fabric are E-glass fibers having adensity of less than 2.60 grams per cubic centimeter. In still another,non-limiting, preferred embodiment, the E-glass fiber yarns, when woveninto a Style 7628 fabric, produce a fabric having a tensile strengthparallel to the warp direction that is greater than the strength (in thewarp direction) of conventionally heat-cleaned and finished fabrics ofthe same style. In one non-limiting embodiment of the pre sentinvention, preferably the resin compatible primary coating compositionis substantially free of “tacky” film-forming materials, i.e., theprimary coating composition comprises preferably less than 10 percent byweight on a total solids basis, more preferably less than 5 percent byweight on a total solids basis.

In a preferred embodiment, the resin compatible primary coatingcomposition is essentially free of “tacky” film-forming materials, i.e.,the primary coating composition comprises preferably less than 1 percentby weight on a total solids basis, more preferably less than 0.5 percentby weight on a total solids basis, and most preferably less than 0.1percent by weight on a total solids basis of tacky film-formingmaterials. Tacky film-forming materials can be detrimental to theweavability of yarns to which they are applied, such as by reducing theair-jet transportability of fill yarns and causing warp yarns to stickto each other. A specific, non-limiting example of a tacky film-formingmaterial is a water-soluble epoxy resin film-forming material.

An alternative method of forming a fabric for use in an electronicsupport application according to the present invention will now bediscussed generally. The method comprises the steps of: (1) obtaining atleast one fill yarn comprising a plurality of glass fibers and having afirst resin compatible coating applied to at least a portion thereof;(2) obtaining at least one warp yarn comprising a plurality of glassfibers and having a second resin compatible coating applied to at leasta portion thereof; and (3) weaving the at least one fill yarn and the atleast one warp yarn having a loss on ignition of less than 2.5 percentby weight to form a fabric adapted to reinforce an electronic support.

A method of forming a laminate adapted for use in an electronic supportwill now be discussed generally. The method comprises a first step ofobtaining a fabric formed by weaving at least one fill yarn comprising aplurality of glass fibers and having a first resin compatible coatingapplied to at least a portion thereof and at least one warp yarncomprising a plurality of glass fibers and having a second resincompatible coating applied to at least a portion thereof wherein thewarp yarn had a loss on ignition of less than 2.5 percent by weightduring weaving. In one, non-limiting embodiment of the presentinvention, preferably, the fabric is essentially free of slashing sizeresidue.

As previously discussed, in typical fabric forming operations, theconventional sizing compositions applied to the glass fibers and/oryarns (i.e., primary sizing compositions and slashing size compositions)are not resin compatible and therefore must be removed from the fabricprior to impregnating the fabric with polymeric resin materials. Asdescribed above, this is most commonly accomplished by heat cleaning thefabric after weaving. However, heat cleaning degrades the strength ofthe glass fibers (and therefore the yarns and fabrics formed therefrom)and causes the glass to densify. The resin compatible coatings of thepresent invention, which are applied to the warp and/or fill yarns priorto weaving, do not require removal prior to impregnation and therebyeliminate the need for heat-cleaning. Therefore, in a preferred,non-limiting embodiment of the present invention, the fabric is freefrom thermal treatment and thermal degradation prior to impregnation.

Additionally, in conventional fabric forming processes, after removal ofthe sizing compositions by heat cleaning, a finishing size must beapplied to the fabric prior to impregnation to improve the compatibilitybetween the fabric and the polymeric resin. By applying a resincompatible coating to the warp and/or fill yarns prior to weaving in thepresent invention, the need for fabric finishing is also eliminated.Therefore, in another preferred embodiment of the present invention, thefabric is preferably substantially free of residue from a secondarycoating and/or a finishing size, i.e., less than 15 percent by weight,more preferably less than 10 percent by weight of residue from asecondary coating and/or a finishing size. In a more preferredembodiment of the present invention, the fabric is essentially free ofresidue from a secondary coating and/or a finishing size. As usedherein, the term “essentially free” means that the fabric has less than1 percent by weight, more preferably less than 0.5 percent by weight ofresidue from a secondary coating and/or a finishing size.

The present invention will now be illustrated by the following specific,non-limiting examples.

EXAMPLE 1

The components in the amounts set forth in Table 1A were mixed to formaqueous forming size compositions A-F according to the present inventionin a similar manner to that discussed above. Less than 1 weight percentof acetic acid was included in each composition. Aqueous forming sizecompositions A-F were coated onto E-glass fiber strands. Each of theforming size compositions had 2.5 weight percent solids. Each coatedglass fiber strand was twisted to form a yarn and wound onto bobbins ina similar manner using conventional twisting equipment. Sample B_(vac)was coated with aqueous forming size composition B, but vacuum dried ata temperature of 190° F. for about 46 hours. Samples A-F each had losson ignition values of less than 1 weight percent. Samples C_(hi) andD_(hi) had loss on ignition values of 1.59 and 1.66 weight percent,respectively.

TABLE 1A WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESCOMPONENT A B C D E F RD-847A⁹¹ 28.6 29.1 31.58 50.71 0 0 DESMOPHEN2000⁹⁸ 43.7 39.1 0 0 0 0 EPI-REZ 3522-W-66⁹⁹ 0 0 21.05 0 0 0 EPON 826¹⁰⁰0 0 0 0 16.12 63.54 PVP-K30¹⁰¹ 0 9.7 15.79 15.21 1.31 5.18 A-187¹⁰² 2.32.3 8.42 8.11 3.17 12.51 A-174¹⁰³ 4.7 4.8 0 0 0 0 A-1100¹⁰⁴ 0 0 8.428.11 0 0 PLURONIC F-108¹⁰⁵ 10.7 5.6 0 0 0 0 IGEPAL CA-630¹⁰⁶ 0 0 4.746.39 1.63 6.44 VERSAMID 140¹⁰⁷ 4.8 4.8 0 0 0 0 ALKAMULS EL-719¹⁰⁸ 0 0 00 1.63 6.44 KESSCO PEG 600¹⁰⁹ 0 0 0 0 0.79 3.11 MACOL NP¹¹⁰ 3.6 3.6 4.746.39 0 0 EMERY 6717¹¹¹ 0 0 0 0 0.40 1.56 EMERY 6760¹¹² 0 0 4.21 4.06 0 0POLYOX WSR-301¹¹³ 0.6 0 0 0 0 0 POLARTHERM PT 1.0 1.0 0 0 74.78 1.00160¹¹⁴ RELEASECOAT- 0 0 1.05 1.01 0 0 CONC 25¹¹⁵ ⁹⁷RD-847A polyesterresin which is commercially available from Borden Chemicals of Columbus,Ohio. ⁹⁸DESMOPHEN 2000 polyethylene adipate diol which is commerciallyavailable from Bayer Corp. of Pittsburgh, Pennsylvania. ⁹⁹EPI-REZ ®3522-W-66 which is commercially available from Shell Chemical Co. ofHouston, Texas. ¹⁰⁰EPON 826 which is commercially available from ShellChemical Co. of Houston, Texas. ¹⁰¹PVP K-30 polyvinyl pyrrolidone whichis commercially available from ISP Chemicals of Wayne, New Jersey.¹⁰²A-187 gamma-glycidoxypropyltrimethoxysilane which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York. ¹⁰³A-174gamma-methacryloxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹⁰⁴A-1100amino-functional organo silane coupling agent which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York.¹⁰⁵PLURONIC ™ F-108 polyoxypropylene-polyoxyethylene copolymer which iscommercially available from BASF Corporation of Parsippany, New Jersey.¹⁰⁶IGEPAL CA-630 ethoxylated octylphenoxyethanol which is commerciallyavailable from GAF Corporation of Wayne, New Jersey. ¹⁰⁷VERSAMID 140polyamide which is commercially available from Cognis Corp. ofCincinnati, Ohio. ¹⁰⁸ALKAMULS EL-719 polyoxyethylated vegetable oilwhich is commercially available from Rhone-Poulenc. ¹⁰⁹KESSCO PEG 600polyethylene glycol monolaurate ester, which is commercially availablefrom Stepan Company of Chicago, Illinois. ¹¹⁰MACOL NP-6 nonylphenolsurfactant which is commercially available from BASF of Parsippany, NewJersey. ¹¹¹EMERY ® 6717 partially amidated polyethylene imine which iscommercially available from Cognis Corp. of Cincinnati, Ohio. ¹¹²EMERY ®6760 lubricant which is commercially available from Cognis Corp. ofCincinnati, Ohio. ¹¹³POLYOX WSR-301 poly(ethylene oxide) which iscommercially available from Union Carbide Corp. of Danbury, Connecticut.¹¹⁴POLARTHERM ® PT 160 boron nitride powder particles, which arecommercially available from Advanced Ceramics Corporation of Lakewood,Ohio. ¹¹⁵ORPAC BORON NITRIDE RELEASECOAT-CONC 25 boron nitride particlesin aqueous dispersion which is commercially available from ZYP Coatings,Inc. of Oak Ridge, Tennessee.

Comparative samples of commercial products 631 and 633 D-450 starch-oilcoated yarns; 690 and 695 starch-oil coated yarns and 1383 G-75 yarnswhich are commercially available from PPG Industries, Inc. were alsoevaluated. In addition, three Comparative Samples X1, X2 and X3, eachcoated with the same aqueous forming composition X set forth in Table 1Bbelow, were also tested. Comparative Sample X1 had 2.5 weight percentsolids. Comparative Sample X2 had 4.9 weight percent solids and was airdried for about 8 hours at 25° C. Comparative Sample X3 had 4.6 weightpercent solids.

TABLE 1B WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS COMPONENTSAMPLE X RD-847A¹¹⁶ 28.9 DESMOPHEN 2000¹¹⁷ 44.1 A-187¹¹⁸ 2.3 A-174¹¹⁹4.8 PLURONIC F-108¹²⁰ 10.9 VERSAMID 140¹²¹ 4.8 MACOL NP-6¹²² 3.6 POLYOXWSR-301¹²³ 0.6 ¹¹⁶RD-847A polyester resin which is commerciallyavailable from Borden Chemicals of Columbus, Ohio. ¹¹⁷DESMOPHEN 2000polyethylene adipate diol which is commercially available from BayerCorp. of Pittsburgh, Pennsylvania. ¹¹⁸A-187gamma-glycidoxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹¹⁹A-174gamma-methacryloxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹²⁰PLURONIC ™ F-108polyoxypropylene-polyoxyethylene copolymer which is commerciallyavailable from BASF Corporation of Parsippany, New Jersey. ¹²¹VERSAMID140 polyamide which is commercially available from Cognis Corp. ofCincinnati, Ohio. ¹²²MACOL NP-6 nonylphenol surfactant which iscommercially available from BASF of Parsippany, New Jersey. ¹²³POLYOXWSR-301 poly(ethylene oxide) which is commercially available from UnionCarbide Corp. of Danbury, Connecticut.

The yarns of Samples A-F and the Comparative Samples were evaluated forloss on ignition (LOI) and air jet compatibility (Air Drag) using the“Air Jet Transport Drag Force” Test Method discussed above in detail.

Each yarn sample was fed at a rate of 274 meters (300 yards) per minutethrough a Sulzer Ruti needle air jet nozzle unit Model No. 044 455 001which had an internal air jet chamber having a diameter of 2 millimetersand a nozzle exit tube having a length of 20 centimeters (commerciallyavailable from Sulzer Ruti of Spartanburg, North Carolina) at an airpressure of 310 kiloPascals (45 pounds per square inch) gauge. Atensiometer was positioned in contact with the yarn at a position priorto the yarn entering the air jet nozzle. The tensiometer providedmeasurements of the gram force (drag force) exerted upon each yarnsample by the air jet as th respective yarn sample was pulled into theair jet nozzle. These values are set forth in Table 1C below.

TABLE 1C Air Jet Transport Drag Force Yarn LOI Drag Force (gram_(force)Type (%) (gram_(force)) per gram_(mass)) Sample No. A G-75 0.35 68.5103,474 B G-75 0.30 84.9 128,248 B_(vac) G-75 0.35 95.0 143,587 C D-4500.52 37.33 278,582 D D-450 0.40 47.1 351,493 E G-75 0.35 79.3 119,789 FG-75 0.35 83.2 125,680 Comparative Samples 631* D-450 1.6 21.45 160,075633* D-450 1.3 38.1 284,328 690* G-75 1.0 108.23 163,489 695* G-75 1.0100.46 151,752 1383 G-75 0.75 14.47 21,858 X1 G-75 0.33 36.4 54,985 X2G-75 0.75 19.0 28,701 X3 D-450 1.37 12.04 89,851 C_(hl) D-450 1.59 9.0067,164 D_(hl) D-450 1.66 10.43 77,836 *Coated with starch-oil sizingformulations.

As shown in Table 1C above, each of the yarns A-F coated with polymericmatrix material compatible sizing compositions according to the presentinvention had Air Jet Transport Drag Values greater than 100,000. Onlythe starch-oil sized commercial strands, which are generallyincompatible with the polymeric matrix materials discussed above, hadAir Jet Transport Drag Values greater than 100,000. Sample yarns C_(hi)and D_(hi), which had polymeric matrix compatible coatings, had Air JetTransport Drag Values less than 100,000 because of high coating levelson the yarns, i.e., loss on ignition greater than 1.5%, which inhibitedseparation of the fibers, or filamentization, of the yarn by the airjet.

To evaluate laminate strength, 7628 style fabrics (style parametersdiscussed above) were formed from samples of 695, Sample B and SampleB_(vac) G-75 yarns (discussed above), respectively. Eight plies of eachfabric sample were laminated with a FR-4 resin system of EPON 1120-A80epoxy resin (commercially available from Shell Chemical Company ofHouston, Tex.), dicyandiamide, 2-methylimidazole and DOWANOL PM glycolether (commercially available from The Dow Chemical Co. of Midland,Mich.) to form laminates.

Each laminate was evaluated for flexural strength (maximum failurestress) testing according to ASTM D-790 and IPC-TM-650 Test MethodsManual of the Institute for Interconnecting and Packaging Electronics(December 1994) (which are specifically incorporated by referenceherein) with metal cladding completely removed by etching according tosection 3.8.2.4 of IPC-4101 and for interlaminar shear strength (shortbeam shear strength) using a 15.9 millimeter (⅝th inch) span andcrosshead speed of 1.27 millimeters (0.05 inches) per minute accordingto ASTM D-2344, which are specifically incorporated by reference herein.The results of these evaluations are shown in Table 1D below.

TABLE 1D Short Beam Flexural Strength Flexural Modulus Shear StrengthSample Pascals psi Pascals Psi Pascals psi B 4.9 × 10⁸ 71534 2.4 × 10¹⁰3465000 2.6 × 10⁷ 3742 B_(vac) 5.0 × 10⁸ 72215 2.4 × 10¹⁰ 3450600 2.5 ×10⁷ 3647 695 4.3 × 10⁸ 62959 2.3 × 10¹⁰ 3360800 2.3 × 10⁷ 3264

As shown in Table ID, Laminate Samples B and B_(vac) prepared accordingto the present invention had higher flexural strength and modulus valuesand similar short beam shear strength when compared to laminate samplesprepared from 695 starch-oil coated glass fiber yarn.

Samples A and B and Comparative Samples 1383 and X1 were also evaluatedfor Friction Force by applying a tension of 30 grams to each yarn sampleas the sample is pulled at a rate of 274 meters (300 yards) per minutethrough a pair of conventional tension measurement devices having astationary chrome post of about 5 centimeters (2 inches) diametermounted therebetween to displace the yarn 5 centimeters from a straightline path between the tension measurement devices. The difference inforce in grams is set forth in Table 1 E below. The Friction Force testis intended to simulate the frictional forces to which the yarn issubjected during weaving operations.

Samples A and B and Comparative Samples 1383 and X1 were also evaluatedfor broken filaments using an abrasion tester. Two hundred grams oftension were applied to each test sample as each test sample was pulledat a rate of 0.46 meters (18 inches) per minute for five minutes throughan abrasion testing apparatus. Two test runs of each sample andcomparative sample were evaluated and the average of the number ofbroken filaments is reported in Table 1 E below. The abrasion testerconsisted of two parallel rows of steel reeds, each row being positioned1 inch apart. Each test yarn sample was threaded between two adjacentreeds of the first row of reeds, then threaded between two adjacentreeds of the second row of reeds, but displaced a distance of one-halfinch between the rows of reeds. The reeds were displaced back and forthover a four inch length in a direction parallel to the direction of yarntravel at a rate of 240 cycles per minute.

TABLE 1E Samples Comparative Comparative Sample No. Sample No. A B 1383X1 Friction force (grams) 24.7 18.3 23.9 38.1 Number of broken 2.0 1.03.8 1.0 filaments per yard of yarn

As shown in Table 1E, Samples A and B, which are coated with sizingcompositions containing boron nitride according to the presentinvention, had few broken filaments and low frictional force whencompared to the Comparative Samples.

EXAMPLE 2

Each of the components in the amounts set forth in Table 2A were mixedto form aqueous forming size compositions G and H according to thepresent invention and a Comparative Sample Y in a similar manner to thatdiscussed above. Less than 1 weight percent of acetic acid on a totalweight basis was included in each composition.

Each of the aqueous forming size compositions E and F of Table 1A inExample 1 and G, H and Comparative Sample Y of Table 2A were coated ontoG-75 E-glass fiber strands. Each of the forming size compositions hadbetween 6 and 25 weight percent solids.

TABLE 2A WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESCOMPONENT G H Comp. Sample Y EPON 826¹²⁴ 16.12 63.54 60.98 PVP K-30¹²⁵1.31 5.18 4.97 ALKAMULS EL-719¹²⁶ 1.63 6.44 6.18 IGEPAL CA-630¹²⁷ 1.636.44 6.18 KESSCO PEG 600¹²⁸ 0.79 3.11 2.98 A-187¹²⁹ 3.17 12.51 12.00EMERY 6717¹³⁰ 0.40 1.56 1.50 PROTOLUBE HD¹³¹ 0 0 4.61 POLARTHERM PT160¹³² 0 0 0 RELEASECOAT-CONC 25¹³³ 74.78 1.00 0 ¹²⁴EPON 826 which iscommercially available from Shell Chemical of Houston, Texas. ¹²⁵PVPK-30 polyvinyl pyrrolidone which is commercially available from ISPChemicals of Wayne, New Jersey. ¹²⁶ALKAMULS EL-719 polyoxyethylatedvegetable oil which is commercially available from Rhone-Poulenc.¹²⁷IGEPAL CA-630 ethoxylated octylphenoxyethanol which is commerciallyavailable from GAF Corporation of Wayne, New Jersey. ¹²⁸KESSCO PEG 600polyethylene glycol monolaurate ester, which is commercially availablefrom Stepan Company of Chicago, Illinois. ¹²⁹A-187gamma-glycidoxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹³⁰EMERY ® 6717partially amidated polyethylene imine which is commercially availablefrom Cognis Corporation of Cincinnati, Ohio. ¹³¹PROTOLUBE HD highdensity polyethylene emulsion which is commercially available fromSybron Chemicals of Birmingham, New Jersey. ¹³²POLARTHERM ® PT 160 boronnitride powder particles, which are commercially available from AdvancedCeramics Corporation of Lakewood, Ohio. ¹³³ORPAC BORON NITRIDERELEASECOAT-CONC 25 boron nitride particles in aqueous dispersion whichis commercially available from ZYP Coatings, Inc. of Oak Ridge,Tennessee.

Each coated glass fiber strand was twisted to form yarn and wound ontobobbins in a similar manner using conventional twisting equipment. Theyarns of Samples F and H exhibited minimal sizing shedding duringtwisting and the yarns of Samples E and G exhibited severe sizingshedding during twisting.

The yarns of Samples E-H and Comparative Sample Y were evaluated for AirDrag in a similar manner to Example 1 above, except that the Air Dragvalues were determined for two bobbin samples at the pressures indicatedin Table 2B. Each yarn was evaluated for average number of brokenfilaments per 1200 meters of yarn at 200 meters per minute using aShirley Model No. 84 041L broken filament detector, which iscommercially available from SDL International Inc. of England. Thesevalues represent the average of measurements conducted on four bobbinsof each yarn. The broken filament values are reported from sectionstaken from a full bobbin, 136 grams (3110 pound) and 272 grams (6/10pound) of yarn unwound from the bobbin.

Each yarn was also evaluated for Gate Tension testing are set forth inTable 2B below. The number of broken filaments measured according to theGate Tension Method is determined by unwinding a sample of yarn from abobbin at 200 meters/minute, threading the yarn through a series of 8parallel ceramic pins and passing the yarn through the Shirley brokenfilament detector discussed above to count the number of brokenfilaments.

TABLE 2B NUMBER OF BROKEN Sample FILAMENTS PER Comp. METER OF YARN E F GH Sample Y full bobbin 0.887 0.241 greater 0.065 0.192 than 10 136 grams(3/10 pound) 0.856 0.017 greater 0.013 0.320 than 10 272 grams (6/10pound) 0.676 0.030 greater 0.101 0.192 than 10 GATE TENSlON (number ofhairs per meter) Gate 2 — 0.039 — 0.0235 0.721 Gate 3 — 0.025 — 0.0280.571 Gate 4 — 0.0125 — 0.068 0.4795 Gate 5 — 0.015 — 0.093 0.85 Gate 6— 0.0265 — 0.118 0.993 Gate 7 — 0.0695 — 0.31 1.0835 Gate 8 — 0.117 —0.557 1.81 AIR DRAG (grams) 25 psi Bobbin 1 — 10.420 — 10.860 11.610Bobbin 2 — 10.600 — 7.850 11.610 30 psi Bobbin 1 — 11.690 — 12.50013.680 Bobbin 2 — 12.200 — 8.540 13.850 35 psi Bobbin 1 — 13.490 —14.030 15.880 Bobbin 2 — 13.530 — 9.570 15.630 40 psi Bobbin 1 — 14.740— 14.110 17.560 Bobbin 2 — 14.860 — 11.010 17.610 45 psi Bobbin 1 —16.180 — 16.390 19.830 Bobbin 2 — 16.680 — 12.700 18.950 50 psi Bobbin 1— 17.510 — 19.280 22.410 Bobbin 2 — 17.730 — 14.000 20.310 55 psi Bobbin1 — 19.570 — 23.350 29.350 Bobbin 2 — 19.660 — 20.250 26.580

While the test results presented in Table 2B appear to indicate thatSamples E-H according to the present invention had generally higherabrasion resistance than 5 the Comparative Sample Y, it is believed thatthese results are not conclusive since it is believed that apolyethylene emulsion component of the Comparative Sample Y, which wasnot present in Samples E-H, contributed to abrasive properties of theyarn.

EXAMPLE 3

Each of the components in the amounts set forth in Table 3A were mixedto form aqueous forming size compositions K through N according to thepresent invention. Each aqueous forming size composition was prepared ina similar manner to that discussed above. Less than 1 weight percent ofacetic acid on a total weight basis was included in each composition.

Each of the aqueous forming size compositions of Table 3A was coatedonto 2G-18 E-glass fiber strands. Each of the forming size compositionshad 10 weight percent solids.

TABLE 3A WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESComparative COMPONENT K L M N Sample Z thermoplastic polyurethane 34.434.2 33.4 31.35 34.5 film-forming polymer¹³⁴ thermoplastic polyurethane51.5 51.2 50.18 46.9 51.7 film-forming polymer¹³⁵ polyoxyalkylene polyol0.3 0.3 0.3 0.3 0.33 copolymer epoxidized polyester lubricant 7.2 7.17.0 6.55 7.22 gamma-aminopropyl 2.7 2.7 2.7 2.5 2.76 triethoxysilanecoupling agent gamma-ureidopropyl 3.3 3.3 3.2 3.0 3.34 triethoxysilanecoupling agent amino-functional organo 0.1 0.1 0.1 0.1 0.14 silanecoupling agent RELEASECOAT- 0.1 1.0 2.9 9.1 0 CONC 25¹³⁶ loss onignition (%) 1.11 1.14 1.05 1.08 1.17 ¹³⁴Thermoplastic polyester-basedpolyurethane aqueous emulsion having 65 percent solids, anionic particlecharge, particle size of about 2 micrometers, a pH of 7.5 and aviscosity of 400 centipoise (Brookfield LVF) at 25° C. ¹³⁵Thermoplasticpolyester-based polyurethane aqueous dispersion having a solids contentof 62 percent, pH of about 10 and average particle size ranging fromabout 0.8 to about 2.5 micrometers. ¹³⁶ORPAC BORON NITRIDERELEASECOAT-CONC 25 boron nitride particles in aqueous dispersion whichis commercially available from ZYP Coatings, Inc. of Oak Ridge,Tennessee.

Composite samples of each of the above coated glass fiber samples andthe Comparative Sample Z were extrusion molded at 270° C. for 48 secondsat 7 MPa (975 psi) to produce 254×254×3.175 millimeters (10×10×0.125inches) plaques. Each specimen was evaluated for: tensile strength,tensile elongation and tensile modulus according to ASTM Method D-638M;flexural strength and flexural modulus according to ASTM Method D-790;and notched and unnotched izod impact strength according to ASTM MethodD-256 at the glass contents specified below.

Table 3B presents the results of tests conducted on composites formedusing a conventional nylon 6,6 matrix resin.

TABLE 3B Samples Comp. units K L M N Sample Z Tensile kpsi 27.1 27.627.3 27.4 26.2 Strength MPa 186.9 190.34 188.27 188.96 180.68 Tensile %3.32 3.37 3.36 3.42 3.32 Elongation Tensile mpsi 1.48 1.55 1.47 1.441.51 Modulus GPa 10.2 l0.7 10.1 9.9 10.4 Flexural kpsi 44.6 46.3 45.745.5 44.0 Strength MPa 307.6 319.3 315.2 313.8 303.4 Flexural mpsi 1.521.56 1.54 1.54 1.5 Modulus GPa 10.5 10.7 10.6 10.6 10.6 notched ftlb₁/in 1.86 2.24 1.94 1.63 1.16 IZOD kJ/m² 7.89 9.50 8.23 6.91 4.92Impact unnotched ft lb₁/in 21.8 22.9 21.1 20.5 22.0 IZOD kJ/m² 92.4397.10 89.46 86.92 93.28 Impact Glass % 32.9 32.6 32.4 32.3 32.4 content

As shown in Table 3B, glass fiber strands coated with boron nitrideparticles (Samples K-N) according to the present invention exhibitimproved tensile strength and notched izod impact properties and similartensile elongation and modulus, flexural strength and modulus andunnotched izod impact properties when compared to a comparative samplehaving similar components which did not contain boron nitride in nylon6,6 reinforcement. When evaluated using nylon 6 resin under similarconditions, the improvements in tensile strength and notched Izod impactproperties were not observed.

EXAMPLE 4

Each of the components in the amounts set forth in Table 4A were mixedto form aqueous forming size compositions P through S according to thepresent invention. Each aqueous forming size composition was prepared ina similar manner to that discussed above. Less than 1 weight percent ofacetic acid on a total weight basis was included in each composition.

Each of the aqueous forming size compositions of Table 4A was coatedonto G-31 E-glass fiber strands. Each of forming size compositions had10 weight percent solids.

TABLE 4A WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESCOMPONENT P Q R S thermoplastic polyurethane film-forming 23 28.75 28.7523 polymer¹³⁷ thermoplastic polyurethane film-forming 34.45 43.1 43.134.45 polymer¹³⁸ polyoxyalkylene polyol copolymer 0.22 0.27 0.27 0.22epoxidized polyester lubricant 4.8 6.0 6.0 4.8 gamma-aminopropyl 1.842.3 2.3 1.84 triethoxysilane coupling agent gamma-ureidopropyl 2.22 2.782.78 2.22 triethoxysilane coupling agent amino-functional organo silane0.1 0.12 0.12 0.1 coupling agent POLARTHERM PT 160¹³⁹ 33.3 16.7 0 0VANTALC 2003¹⁴⁰ 0 0 16.7 33.3 loss on ignition (%) 0.52 0.81 0.80 0.64¹³⁷Thermoplastic polyester-based polyurethane aqueous emulsion having 65percent solids, anionic particle charge, particle size of about 2micrometers, a pH of 7.5 and a viscosity of 400 centipoise (BrookfieldLVF) at 25° C. ¹³⁸Thermoplastic polyester-based polyurethane aqueausdispersion having a solids content of 62 percent, pH of about 10 andaverage particle size ranging from about 0.8 to about 2.5 micrometers.¹³⁹POLARTHERM ® PT 160 boron nitride powder particles, which arecommercially available from Advanced Ceramics Corporatan of Lakewoad,Ohio. ¹⁴⁰VANTALC 2003 talc powder particles, which are commerciallyavailable from R. T. Vanderbilt Company, Inc. of Norwalk, Connecticut.

Composite samples of each of the above coated glass fiber samples andthe Comparative Sample Z of Table 3A above were extrusion molded toproduce 400×400×2.5 millimeters (16×16×0.100 inches) plaques under theconditions set forth in Example 3 above. Each specimen was evaluatedfor: tensile strength, tensile elongation, tensile modulus, notched andunnotched izod impact strength as discussed in Example 3 above at theglass contents specified below.

The color tests were performed on composites having a thickness of 3.175millimeters (⅛ inch) and a diameter of 76.2 millimeters (3 inches) usinga Hunter calorimeter Model D25-PC2A. To evaluate material handlingcharacteristics, funnel flow tests were conducted on samples of choppedglass fiber. The funnel was eighteen inches long and had a seventeeninch diameter opening at the top and a two inch opening on the bottom.The funnel was vibrated and the time was recorded for 20 pounds ofsample material to flow through the funnel. The PD-104 test evaluatesthe resistance of the chopped glass fiber sample to filamentation. Sixtygrams of sample, 140 grams of an abrasive material (ground walnut shellparticles No. 6/10 which are commercially available from Hammon ProductsCompany) and a conventional foam type antistatic dryer sheet wereenclosed in a 4 liter stainless steel beaker and vibrated using a RedDevil paint shaker Model 5400E3 for six minutes. The vibrated materialwas screened using No. 5 and No. 6 U.S. Standard testing sieves. Theweight percent of fuzz material collected on the screens as a percentageof original sample is reported below.

Table 4B presents the results of tests conducted on composites formedusing Samples P—S and Comparative Sample Z using nylon 6,6 matrix resin.

TABLE 4B Samples Comp. units K L M N Sample Z Tensile kpsi 29.5 28.628.7 27.7 29.6 Strength Mpa 203.5 197.2 197.9 191.0 204.1 Tensile % 3.033.05 2.98 2.97 3.01 Elongation Tensile kpsi 1866 1779 1720 1741 1748Modulus Gpa 12.86 12.26 11.86 12.0 12.05 notched ft lb₁/in 2.10 1.961.94 1.78 2.26 IZOD kJ/m² 8.90 8.31 8.23 7.55 9.58 Impact unnotched ftlb₁/in 24.9 23.4 22.8 22.2 26.4 IZOD kJ/m² 105.58 99.22 96.67 94.13111.94 Impact Actual Loss % 0.81 0.52 0.80 0.64 1.17 on Ignition PD 104% 1.3 0.7 0.1 1.4 0.1 Funnel Flow seconds 13.8 15.2 15.4 23.5 13.0Whiteness −15.1 −12.0 −17.6 −18.5 −18.2 Index Yellowness 40.0 37.5 42.543.4 43.6 Index Glass 33.30 33 32.90 31.70 33.80 content

As shown in Table 4B, glass fiber strands coated with boron nitrideparticles (Samples P-S) according to the present invention exhibitimproved whiteness and yellowness and similar tensile strength,elongation and modulus, flexural strength and modulus, and notched andunnotched izod impact properties when compared to a Comparative Sample Zhaving similar components which did not contain boron nitride in nylon6,6 reinforcement.

EXAMPLE 5

Each of the components in the amounts set forth in Table 5 were mixed toform aqueous forming size compositions T and U according to the presentinvention. Each aqueous forming size composition was prepared in asimilar manner to that discussed above. Less than about 1 weight percentof acetic acid on a total weight basis was included in each composition.Table 5A presents the results of whiteness and yellowness testsconducted on composites formed using Samples T, U and Comparative SampleZ (as discussed in Table 3A of Example 3 and repeated below) using nylon6,6 matrix resin. The color tests were performed on composites having athickness of 3.175 millimeters (⅛ inch) and a diameter of 76.2millimeters (3 inches) using a Hunter calorimeter Model D25-PC2A.

TABLE 5 WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESComparative COMPONENT T U Sample Z thermoplastic polyurethane 31.3528.75 34.5 film-forming polymer¹⁴¹ thermoplastic polyurethane 46.9 43.151.7 film-forming polymer¹⁴² polyoxyalkylene polyol copolymer 0.3 0.270.3 epoxidized polyester lubricant 6.55 6.0 7.22 gamma-aminopropyl 2.52.3 2.76 triethoxysilane coupling agent gamma-ureidopropyl 3.0 2.78 3.34triethoxysilane coupling agent amino-functional organo silane 0.1 0.120.14 coupling agent RELEASECOAT-CONC 25¹⁴³ 9.1 16.7 0 Whiteness Index−16.3 −15.0 −20.7 Yellowness Index 39.3 38.1 42.7 ¹⁴¹Thermoplasticpolyester-based polyurethane aqueous emulsion having 65 percent solids,anionic particle charge, particle size of about 2 micrometers, a pH of7.5 and a viscosity of 400 centipoise (Brookfield LVF) at 25° C.¹⁴²Thermoplastic polyester-based polyurethane aqueaus dispersion havinga solids content of 62 percent, pH of about 10 and average particle sizeranging from about 0.8 to about 2.5 micrometers. ¹⁴³ORPAC BORON NITRIDERELEASECOAT-CONC 25 boron nitride particles in aqueous dispersion whichis commercially available from ZYP Coatings, Inc. of Oak Ridge,Tennessee.

As is shown in Table 5, Samples T and U, each coated with a sizingcomposition containing boron nitride particles according to the presentinvention, had lower whiteness indices in nylon 6,6 than a ComparativeSample Z of a similar formulation which did not include boron nitride.

EXAMPLE 6

Five layers of ADFLO-C™ needled chopped glass fiber mat, which iscommercially available from PPG Industries, Inc., were stacked to form amat having a surface weight of 4614 grams per square meter (about 15ounces per square foot). The thickness of each sample was 25 millimeters(about 1 inch). Four eight-inch square samples of this mat were heatedto a temperature of 649° C. (about 1200° F.) to remove essentially allof the sizing components from the samples.

Two uncoated samples were used as comparative samples (“ComparativeSamples”). The other two samples (“Sample X”) were dipped and saturatedin a bath of an aqueous coating composition consisting of 1150milliliters of ORPAC BORON NITRIDE RELEASECOAT-CONC (25 weight percentboron nitride particles in an aqueous dispersion) and 150 milliliters ofa 5 weight percent aqueous solution of A-187gamma-glycidoxypropyltrimethoxysilane. The total solids of the aqueouscoating composition was 18.5 weight percent. The amount of boron nitrideparticles applied to each mat sample was 120 grams. The coated matsamples were dried in air overnight at a temperature of 25° C. andheated in an oven at 150° C. for three hours.

Each set of samples was evaluated for thermal conductivity and thermalresistance in air at temperatures of 300 K (about 70° F.) according toASTM Method C-177, which is specifically incorporated by referenceherein. The values for thermal conductivity and thermal resistance foreach sample are set forth in Table 6 below.

TABLE 6 Sample X Comp. Sample Thickness (inches) 1.09 1.0 (centimeters)2.77 2.54 Temperature (° F.) 75.62 74.14 (° C.) 24.23 23.41 Thermalconductivity Btu inches per hour square feet ° F. 0.373 0.282 Watts permeter K 0.054 0.041 Thermal r sistanc Hour square feet ° F. per BTU 2.923.55 Meter² K per Watts 0.515 0.626

Referring to Table 6, the thermal conductivity at a temperature 300K ofthe test sample coated with boron nitride particles according to thepresent invention was greater than the thermal conductivity of theComparative Sample which was not 5 coated with boron nitride particles.

EXAMPLE 7

Filament wound cylindrical composites were prepared from samples of G-75yarn coated with sizing G of Example 2 above and 1062 glass fiber yarnthat is commercially available from PPG Industries, Inc. The cylinderswere prepared by drawing eight ends of yarn from a yarn supply, coatingthe yarn with the matrix materials set forth below, and filament windingthe yarn into a cylindrical shape using a conventional filament windingapparatus. Each of the cylinders was 12.7 centimeters (5 inches) high,had an internal diameter of 14.6 centimeters (5.75 inches) and a wallthickness of 0.635 centimeters (0.25 inches).

The matrix materials were a mixture of 100 parts EPON 880 epoxy resin(commercially available from Shell Chemical), 80 parts AC-220J methyltetrahydro phthalic anhydride (commercially available from Anhydridesand Chemicals, Inc. of Newark, N.J.), and 1 part ARALDITE® DY 062 benzyldimethyl amine accelerator (commercially available from Ciba-Geigy). Thefilament wound cylinders were cured for two hours at 100° C. and thenfor three hours at 150° C.

The radial thermal diffusivity (thermal conductivity/(heatcapacity×density) ) of each test sample in air was determined byexposing one side of the cylinder wall of the sample to a 6.4 kJ flashlamp and sensing the temperature change on the opposite side of the wallusing a CCD array infrared camera at a rate of up to 2000 frames persecond. Thermal diffusivity values were also determined along a lengthof the yarn (circumferential) and along a length or height of thecylinder (axial). The test results are set forth below in Table 7.

TABLE 7 Thermal Diffusivity (mm²/sec) radial axial circumferentialSample 0.37 0.33 0.49 Comparative Sample 0.38 0.38 0.57

Referring to Table 7, the values of thermal diffusivity for the testsample (which was coated with a small amount of boron nitride) are lessthan those of the comparative sample, which was not coated with boronnitride. Air voids in the filament wound cylinder and the small samplearea tested are factors that may have influenced these results.

EXAMPLE 8

The coefficient of thermal expansion in the z-direction of a laminate(“Z-CTE”), i.e., across the thickness of the laminate, was evaluated forlaminate samples, each containing eight layers of 7628 style fabricprepared from samples of B_(vac) coated yarn (discussed in Example 1)and 695 starch-oil coated yarns (discussed in Example 1) (Control). Thelaminate was prepared using the FR-4 epoxy resin discussed in Example 1above and clad with copper according to IPC Test Method 2.4.41, which isspecifically incorporated by reference herein. The coefficient ofthermal expansion in the z-direction was evaluated for each laminatesample at 288° C. according to IPC Test Method 2.4.41. The results ofthe evaluations are shown in Table 8 below.

TABLE 8 Sample Z-CTE (%) Sample B_(vac)1 4.10 Sample B_(vac)1 (retest)4.41 Sample B_(vac)2 4.06 Sample B_(vac)2 (retest) 4.28 Sample B_(vac)34.17 Sample B_(vac)3 (retest) 4.26 Control 1 5.0 Control 2 5.4

As shown in Table 8, for laminate Samples A1-A3 according to the presentinvention, the coefficients of thermal expansion in the z-direction ofthe laminates are less than those of Control Samples 1 and 2, which wereprepared from 695 starch-oil coated yarn.

EXAMPLE 9

Each of the components in the amounts set forth in Table 9A were mixedto form aqueous primary size compositions AA, BB and CC according to thepresent invention. Each aqueous primary sizing composition was preparedin a similar manner to that discussed above. Less than 1 weight percentof acetic acid on a total weight basis was included in each composition.Each of the aqueous sizing compositions of Table 9A was coated ontofibers forming G-75 E-glass fiber strands.

Each of the coated glass fiber strands was dried, twisted to form yarn,and wound onto bobbins in a similar manner using conventional twistingequipment. The yarns coated with the sizing compositions exhibitedminimal sizing shedding during twisting.

TABLE 9A WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESCOMPONENT AA BB CC PVP K-30¹⁴⁴ 14.7 14.7 13.4 STEPANTEX 653¹⁴⁵ 30.0 29.927.3 A-187¹⁴⁶ 1.8 1.8 1.6 A-174¹⁴⁷ 3.7 3.7 3.3 EMERY 6717¹⁴⁸ 2.4 2.4 2.2MACOL OP-10¹⁴⁹ 1.6 1.6 1.5 TMAZ-81¹⁵⁰ 3.3 3.3 3.0 MAZU DF-136¹⁵¹ 0.2 0.20.2 ROPAQUE HP-1055¹⁵² 0 42.4 0 ROPAQUE OP-96¹⁵³ 42.3 0 38.6RELEASECOAT-CONC 25¹⁵⁴ 0 0 6.3 POLARTHERM PT 160¹⁵⁵ 0 0 2.6 ¹⁴⁴PVP K-30polyvinyl pyrrolidone which is commercially available from ISP Chemicalsof Wayne, New Jersey. ¹⁴⁵STEPANTEX 653 which commercially available fromStepan Company of Maywood, New Jersey. ¹⁴⁶A-187gamma-glycidoxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹⁴⁷A-174gamma-methacryloxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹⁴⁸EMERY ® 6717partially amidated polyethylene imine which is commercially availablefrom Cognis Corporation of Cincinnati, Ohio. ¹⁴⁹MACOL OP-10 ethoxylatedalkylphenol; this material is similar to MACOL OP-10 SP except thatOP-10 SP receives a post treatment to remove the catalyst; MACOL OP-10is no longer commercially available. ¹⁵⁰TMAZ-81 ethylene oxidederivative of a sorbitol ester which is commercially available from BASFCorp. of Parsippany, New Jersey. ¹⁵¹MAZU DF-136 anti-foaming agent whichis commercially available from BASF Corp. of Parsippany, New Jersey.¹⁵²ROPAQUE ® HP-1055, 1.0 micron particle dispersion which iscommercially available from Rohm and Haas Company of Philadelphia,Pennsylvania. ¹⁵³ROPAQUE ® OP-96, 0.55 micron particle dispersion whichis commercially available from Rohm and Haas Company of Philadelphia,Pennsylvania. ¹⁵⁴ORPAC BORON NITRIDE RELEASECOAT-CONC 25 boron nitridedispersion which is commercially available from ZYP Coatings, Inc. ofOak Ridge, Tennessee. ¹⁵⁵POLARTHERM ® PT 160 boron nitride powder whichis commercially available from Advanced Ceramics Corporatan of Lakewood,Ohio.

Yarns sized with the each of the sizing compositions (AA, BB and CC)were used as fill yarn in weaving a 7628 style fabric using a SulzerRuti Model 5200 air-jet loom. The warp yarn was a twisted G-75 E-glassfiber strand with fiber coated with a different resin compatible sizingcomposition¹⁵⁶. The fabrics were subsequently prepregged with an FR-4epoxy resin having a Tg of 140° C. (designated 4000-2 resin by NelcoInternational Corporation of Anaheim, Calif.). The sizing compositionswere not removed from the fabric prior to prepregging. Laminates weremade by stacking 8-plies of the prepregged material between two layersof 1 ounce copper and laminating them together at a temperature of 355°F. (about 179° C.), pressure of 300 pounds per square inch (about 2.1megapascals) for 150 minutes (total cycle time). The thickness of thelaminates without copper ranged from 0.043 inches (about 0.11centimeters) to 0.050 inches (about 0.13 centimeters).

¹⁵⁶The warp yarn was PPG Industries, Inc.'s commercially available fiberglass yarn product designated as G-75 glass fiber yarn coated with PPGIndustries, Inc.'s 1383 binder.

After forming, the laminates designated AA, BB and CC according to thefiber strands from which they were made) were tested as indicated belowin Table 9B. During testing, laminate BB tested at the same time as afirst laminate made from glass fiber yarn coated with sizing compositionSample AA (hereinafter designated as Laminate Sample AA1). At a laterdate, laminate CC was tested at the same time as a second laminate madefrom glass fiber yarn coated with sizing composition Sample CC(hereinafter designated as Laminate Sample AA2).

TABLE 9B Laminate Sample Test Units AA1* BB* AA2** CC** Average inches0.048 0.048 0.053-0.055 0.053-0.055 Thickness Solder Float seconds 409386 235 253 Solder Dip seconds 320 203 243 242 Flexural kpsi 99 102 9190 Strength Warp Direction¹⁵⁷ Flexural kpsi 86 81 73 72 Strength WeftDirection¹⁵⁸ *based on 2 samples **based on 3 samples ¹⁵⁶The warp yarnwas PPG Industries, Inc.'s commercially available fiber glass yarnproduct designated as G-75 glass fiber yarn coated with PPG Industries,Inc.'s 1383 binder. ¹⁵⁷Per IPC-TM-650 “Flexural Strength of Laminates(At Ambient Temperature)”, December 1984, Revision B. ¹⁵⁸Per IPC-TM-650“Flexural Strength of Laminates (At Ambient Temperature)”, December1984, Revision B.

The solder float test was conducted by floating an 4 inch by 4 inchsquare (10.16 centimeters by 10.16 centimeters) of the copper dadlaminate in a eutectic lead-tin solder bath at 550° F. (about 288° C.)until blistering or delamination was observed. The time until the firstblister or delamination was then recorded in seconds.

The solder dip test was conducted by cutting a sample of the laminate,removing the copper from the sample by etching, smoothing the cut edgesof the sample by polishing and placing the sample in a pressure cookerat 250° F. (about 121° C.) and 15 pounds per square inch (about 0.1megaPascals) for 60 minutes. This test is the pressure cooker testreferred to in the following table. After the 60 minute exposure, thesample was removed from the pressure cooker, patted dry and dipped intoa eutectic lead-tin solder bath at 550° F. (about 288° C.) untilblistering or delamination was observed. The time until the firstblister or delamination was then recorded in seconds.

The flexural testing was conducted according to the IPC standardindicated.

The laminates M, BB and CC made using fiber strands sized with sizingcompositions M, BB and CC respectively, had acceptable properties (shownin Table 9B) for use as electronic supports for printed circuit boards.

The following tests were also performed on samples AA, BB and CC, andare set forth in Table 9C.

TABLE 9C Samples Test Units AA BB CC Tg by DSC ° C. 141/140/139140/141/141 138/140/139 0/30/60 min Pressure % Moisture 0.37 0.37 0.38Cooker Uptake Water % Weight 0.12 0.09 0.09 Resistance¹⁵⁹ Gain DMF %Weight 0.35 0.27 0.29 Resistance Gain MeCl₂ % Weight 0.77 0.82 0.68Resistance¹⁶⁰ Gain Copper Peel Pounds 11.8/11.0 12.1/11.1 11.2/11.4Strength¹⁶¹ (Warp/Fill) Interlaminar Pounds 12.8 14.2 15.4 Bond per inchStrength¹⁶² ¹⁵⁹Per IPC-TM-650, No. 2.6.2.1, “Water Absorption, MetalClad Plasitc Laminates”, May 1986, Revision A. ¹⁶⁰Per IPC-TM-650, No.2.3.4.3, “Chemical Resistance of Core Materials to Methylene Chloride”,May 1986. ¹⁶¹Per IPC-TM-650, No. 2.4.8, “Peel Strength: As Received,After Thermal Stress, After Process Chemicals”, January 1986, RevisionB. ¹⁶²Per IPC-TM-650, No. 2.4.40, “Inner Layer Bond Strength ofMultilayer Printed Circuit Boards”, October 1987.

EXAMPLE 10

Each of the components in the amounts set forth in Table 10 were mixedto form aqueous size composition Samples DD, EE and FF according to thepresent invention. Less than 0.5 weight percent of acetic acid on atotal weight basis was included in each composition.

TABLE 10 WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESCOMPONENT DD EE FF PVP K-30¹⁶³ 12.3 11.7 12.3 STEPANTEX 653¹⁶⁴ 25.0 23.925.0 TMAZ 81¹⁶⁵ 3.5 3.9 2.7 MACOL OP-10¹⁶⁶ 1.8 2.0 1.4 POLARTHERM PT160¹⁶⁷ 2.4 2.3 2.4 EMERY 6717¹⁶⁸ 2.0 2.0 2.0 A-174¹⁶⁹ 3.1 2.9 3.1A-187¹⁷⁰ 1.5 1.4 1.5 RELEASECOAT-CONC 25¹⁷¹ 5.7 5.5 5.6 MAZU DF-136¹⁷²0.2 0.2 0.2 ROPAQUE OP-96¹⁷³ 35.2 33.7 35.3 FLEXOL LOE¹⁷⁴ 7.3 10.5 0FLEXOL EPO¹⁷⁵ 0 0 7.3 Weight percent solids 3.4 3.5 3.4 LOI 0.42 0.390.30 ¹⁶³PVP K-30 polyvinyl pyrrolidone which is commercially availablefrom ISP Chemicals of Wayne, New Jersey. ¹⁶⁴STEPANTEX 653 cetylpalmitate which is commercially available from Stepan Company ofChicago, Illinois. ¹⁶⁵TMAZ 81 ethylene oxide derivative of a sorbitolester which is commercially available BASF of Parsippany, New Jersey.¹⁶⁶MACOL OP-10 ethoxylated alkylphenol; this material is similar tcMACOL OP-10 SP except that OP-10 SP receives a post treatment to removethe catalyst; MACOL OP-10 is no longer commercially available.¹⁶⁷POLARTHERM ® PT 160 boron nitride powder particles, which arecommercially available from Advanced Ceramics Corporation of Lakewood,Ohio. ¹⁶⁸EMERY ® 6717 partially amidated polyethylene imine which iscommercially available from Cognis Corporation of Cincinnati, Ohio.¹⁶⁹A-174 gamma-methacryloxypropyltrimethoxysilane which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York. ¹⁷⁰A-187gamma-glycidoxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹⁷¹ORPAC BORON NITRIDERELEASECOAT-CONC 25 boron nitride dispersion which is dispersion ofabout 25 weight percent boron nitride particles in water commerciallyavailable from ZYP Coatings, Inc. of Oak Ridge, Tennessee. ¹⁷²MAZUDF-136 anti-foaming agent which is commercially available from BASFCompany of Parsippany, New Jersey. ¹⁷³ROPAQUE ® OP-96, 0.55 micronparticle dispersion which is commercially available from Rohm and HaasCompany of Philadelphia, Pennsylvania. ¹⁷⁴FLEXOL LOE epoxidized linseedoil commercially available from Union Carbide Corp. of Danbury,Connecticut. ¹⁷⁵FLEXOL EPO epoxidized soybean oil commercially availablefrom Union Carbide Corp. of Danbury, Connecticut. ¹⁷⁶The warp yarn wasPPG Industries, Inc.'s commercially available fiber glass yarn productdesignated as G-75 glass fiber yarn coated with PPG Industries, Inc.'s1383 binder.

Each of the aqueous size compositions of Table 10 was used to coat glassfibers forming G-75 E-glass fiber strands. Each coated glass fiberstrand was dried, twisted to form a yarn, and wound onto bobbins in asimilar manner using conventional twisting equipment.

The yarn of Sample DD was evaluated by comparing the coated yarn to yarncoated with a sizing composition similar to Sample DD but without theepoxidized linseed oil (hereinafter “Comparative Sample 1”). Thiscomparison included visual inspection of the appearance of a 7628 stylefabric woven on an air jet loom. The woven fabric used Sample DD as thefill yarn a twisted G-75 E-glass fiber strand with fiber coated with adifferent resin compatible sizing composition¹⁷⁶ as the warp yarn. Itwas observed that fabric woven with yarn coated with Sample DD exhibitedless loose fuzz on the fabric as well as less collected fuzz at contactpoints on the loom, especially at the yarn accumulator, when compared tofabric woven with yarn coated with Comparative Sample 1. No fabric waswoven using yarn incorporating fibers coated with Samples EE or FFbecause of the high initial amount of fuzz observed on the loom. It isbelieved that this condition was the result of an LOI level lower thanrequired to prevent excess fuzz formation. In the present invention, itis anticipated that an LOI of at least 0.40 for the sizing compositionsdiscussed above is required to reduce fuzz formation during weaving.

¹⁷⁶The warp yarn was PPG Industries, Inc.'s commercially available fiberglass yarn product designated as G-75 glass fiber yarn coated with PPGIndustries, Inc.'s 1383 binder.

EXAMPLE 11

The yarns of Samples AA, BB and CC and a Comparative Sample 2¹⁷⁷ (yarncoated with a starch/oil sizing) were evaluated for several physicalproperties, such as loss on ignition (LOI), air jet compatibility (AirDrag) and Friction Force. The results are shown in Table 11.

¹⁷⁷ The yarn was PPG Industries, Inc.'s commercially available fiberglass yarn designated as G-75 glass fiber yarn coated with PPGIndustries, Inc.'s 695 starch/oil binder.

The loss on ignition (weight percent of solids of the forming sizecomposition divided by the total weight of the glass and dried formingsize composition) of each Sample is set forth in Table 11.

Each yarn was evaluated for Air Drag Force or tension by feeding theyarn at a controlled feed rate of 274 meters (300 yards) per minutethrough a checkline tension meter, which applied a tension to the yarn,and a Ruti two millimeter diameter air nozzle at an air pressure of 138kPa (20 pounds per square inch).

The Samples and Comparative Sample 2 were also evaluated for FrictionForce by applying a tension of 20 grams to each yarn sample as thesample is pulled at a rate of 274 meters (300 yards) per minute througha pair of conventional tension measurement devices having a stationarychrome post of 5 centimeters (about 2 inches) diameter mountedtherebetween to displace the yarn 5 centimeters from a straight linepath between the tension measurement devices. The difference in force ingrams is set forth in Table 11 below. The Friction Force test isintended to simulate the frictional forces to which the yarn issubjected during weaving operations.

During testing, Sample BB and Comparative Sample 2 were tested at thesame time as a first quantity of glass fiber yarn coated with sizingcomposition Sample AA (hereinafter designated as Sample AA3) and SampleCC was tested at the same time as a second quantity of glass fiber yarncoated with sizing composition Sample AA (hereinafter designated asSample AA4). Samples AA3, AA4 and BB were 2.8 weight percent solids.Sample CC was 3.1 weight percent solid. Comparative Sample 2 was 5.9weight percent solid.

TABLE 11 Sample AA3 BB 2 AA4 CC LOI (weight percent) 0.42 0.49 1.11 0.380.37 Air Drag (grams) 56.2 51.2 52.9 58.8 53.2 Friction force (grams)53.6 61.5 95.1 48.8 68.9

From Table 11, it can be seen that sizing Samples M, BB and CC have anair drag comparable to that of Comparative Sample 2 (starch/oil binder).Furthermore, the lower friction force in Samples AA, BB and CC indicatesthat the yarn is more easily removed from the loom accumulator duringweaving when compared to Comparative Sample 2.

EXAMPLE 12

The yarns of Samples AA, BB and CC and Comparative Sample 2 wereevaluated for Air Drag in a similar manner to Example 11 above, exceptthat the Air Drag values were determined for a bobbin sample at thepressures indicated in Table 12.

Each yarn also was evaluated for average number of broken filaments per1200 meters of yarn at 200 meters per minute using a Shirley Model No.84 041L broken filament detector, which is commercially available fromSDL international Inc. of England (shown in Table 12 as Test 1). Thebroken filament values are reported from sections taken from a fullbobbin, the same bobbin after removing 227 grams (0.5 pounds) and thesame bobbin after removing 4540 grams (10 pounds) of yarn. Each yarn wasfurther evaluated for the number of broken filaments at increasinglevels of tension and abrasion (shown in Table 12 as Test 2). In Test 2,a sample of yarn was unwound from a bobbin at 200 meters/minute,threaded in a serpentine manner through a series of 8 ceramic pins on auniform tension control device (sometimes referred to as a gatetensioning device), and passed through the Shirley broken filamentdetector (discussed above) to count the number of broken filaments. Thespacing of the pins on the tensioning device was varied using differentdial settings to provide various levels of tension in the yarn. Thisparticular test used a Model UTC-2003 tensioning device commerciallyavailable from Steel Heddle Co. of South Carolina. The broken filamentswas reported in number of broken filaments per meter of yarn.

The results of these tests for Samples M, BB and CC and ComparativeSample 2 are set forth in Table 12 below. In a manner similar to thatdiscussed above in Example 11, Sample BB and Comparative Sample 2 weretested at the same time as a first quantity of glass fiber yarn coatedwith sizing composition Sample AA (hereinafter designated as Sample AA5)and at a latter date Sample CC was tested at the same time as a secondquantity of glass fiber yarn coated with sizing composition Sample M(hereinafter designated as Sample AA6).

TABLE 12 Sample AA5 BB 2 AA6 CC AIR DRAG (grams) 15 psi 46.10 42.5042.23 47.47 42.33 20 psi 56.20 51.20 52.94 58.84 53.18 25 psi 67.3360.30 64.13 69.45 67.66 30 psi 77.34 70.84 75.74 75.29 77.63 35 psi89.42 89.96 85.96 83.70 82.74 40 psi 104.97 101.21 98.48 87.23 92.18 45psi 113.41 107.74 110.34 99.91 102.91 TEST 1 full bobbin 0.170 0.8820.032 1.735 0.066  227 grams (0.5 pound) 0.160 0.648 0.041 0.904 0.0754540 grams (10 pounds) 0.098 1.348 0.008 0.518 0.022 TEST 2 Setting 20.683 5.017 0.119 0.372 0.011 Setting 3 0.753 4.772 0.083 0.450 0.017Setting 4 0.713 3.753 0.147 0.367 0.017 Setting 5 1.267 4.025 0.1500.811 0.061 Setting 6 1.608 8.383 0.322 0.286 0.044 Setting 7 4.1286.517 0.611 0.403 0.058 Setting 8 4.472 14.800 0.978 0.408 0.128

As can be seen in Table 5, sizing Samples M, BB and CC have an air dragcomparable to that of Comparative Sample 2 (starch/oil binder).

EXAMPLE 13

Electrical grade laminates made from prepregs incorporating fabrics withyarns having different sizing compositions were tested to evaluate theirdrilling properties, and more specifically (i) the drill tip wear ofdrills used to drill holes through the laminates and (ii) the locationalaccuracy of the holes drilled through the laminates. Control GG andSample HH were laminates incorporating a 7628 style fabric as discussedearlier. The fabric in Control GG was a heat cleaned and silane finishedfabric commercially available from Clark Schwebel and identified as7628-718. The fabric in Sample HH was woven from fill yarn comprisingglass fibers coated with a resin compatible sizing as taught herein andshown in Table 13A. It is believed that the fabric also included SampleHH as the warp yarn. However, it is possible that the warp yarn couldhave been PPG Industries, Inc.'s 1383 commercially available fiber glassyarn product. The glass fibers woven into Sample HH had a loss onignition of 0.35 percent.

TABLE 13A Weight Percent of Components on Total Solids Basis for Sizingused in Sample HH COMPONENT SAMPLE HH RD-847A¹⁷⁸ 27.0 DESMOPHEN 2000¹⁷⁹36.2 PVP K-30¹⁸⁰ 9.0 A-187¹⁸¹ 2.1 A-174¹⁸² 4.4 PLURONIC F-108¹⁸³ 9.0VERSAMID 140¹⁸⁴ 4.4 MACOL NP-6¹⁸⁵ 5.4 POLARTHERM PT 160¹⁸⁶ 0.9RELEASECOAT-CONC 25¹⁸⁷ 1.5 acetic acid <0.1 ¹⁷⁸RD-847A polyester resin,which is commercially available from Borden Chemicals of Columbus, Ohio.¹⁷⁹DESMOPHEN 2000 polyethylene adipate diol, which is commerciallyavailable from Bayer Corp. of Pittsburgh, Pennsylvania. ¹⁸⁰PVP K-30polyvinyl pyrrolidone, which is commercially available from ISPChemicals of Wayne, New Jersey. ¹⁸¹A-187gamma-glycidoxypropyltrimethoxysilane, which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹⁸²A-174gamma-methacryloxypropyltrimethoxysilane, which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York.¹⁸³PLURONIC ™ F-108 polyoxypropylene-polyoxyethylene copolymer, which iscommercially available from BASF Corporation of Parsippany, New Jersey.¹⁸⁴VERSAMID 140 polyamide, which is commercially available Cognis Corp.of Cincinnati, Ohio. ¹⁸⁵MACOL NP-6 nonyl phenol surfactant, which iscommercially available from BASF Corporation of Parsippany, New Jersey.¹⁸⁶POLARTHERM ® PT 160 boron nitride powder particles, which arecommercially available from Advanced Ceramics Corporation of Lakewood,Ohio. ¹⁸⁷ORPAC BORON NITRIDE RELEASECOAT-CONC 25, which is commerciallyavailable from ZYP Coatings, Inc. of Oak Ridge, Tennessee.

Prepregs were prepared by a hand lay-up procedure that involved applyingstandard FR-4 epoxy-resin (EPON 1120-A80 resin available from ShellChemical Co.) to the fabrics using a paintbrush. The resin saturatedfabric was immediately “dried” and B-staged in a vented hot air oven for3 to 3.25 minutes at 163° C. (about 325° F.) until the desired gel timeof 124 seconds at 171° C. (about 340° F.) was reached. The prepregs weretrimmed to 46 cm by 46 cm (18 inch by 18 inch) sections and weighed todetermine resin content. Only prepregs with resin contents of 44percent±2 percent were used in the subsequent laminating procedure.

Prepregs were stacked 8 high and molded in a Wabash Press for 70 minutesat 177° C. (350° F.) and at 345 newtons/cm² (500 psi). All the laminateswere molded without copper foil layers. The laminates showed variouslevels of air entrapment. It is believed that the lack of vacuum assistand temperature ramping during lamination contributed to this condition.

Tool Wear Analysis

The first series of tests were conducted to evaluate the wear of thedrill tip. The tip wear was expressed in terms of “drill tip percentwear” which was calculated using the formula:drill tip percent wear=100×(P _(i) −P _(f))/P _(i)

-   -   where        -   P_(i)=initial width of the primary cutting edge        -   P_(f)=width of the primary cutting edge after the allotted            holes were drilled.

Referring to FIG. 11, the width 1170 of the primary cutting edge 1172 ofthe drill 1174 was measured at the peripheral edge of the drill tip.

The drilling was conducted using a single head drilling machine. Thedrilling was performed on 3-high stacks of laminates (discussed above)with a 0.203 mm (0.008 inch) thick aluminum entry and 1.88 mm (0.074inch) thick paper core phenylic coated back-up. Drilling 3 laminates atone time is generally standard practice in the industry. The drill tippercent wear was determined for two drill diameters: 0.35 mm (0.0138inches) and 0.46 mm (0.018 inches). Both drills were a series 508tungsten carbide drill available from Tulon Co., Gardenia, Calif. Thechip load during drilling was held constant at 0.001 for each tool. Asused herein, “chip load” means the ratio of the drill insertion ratemeasured in inches per minute to the spindle speed measured inrevolutions per minute (rpm). For the 0.35 mm drill, the spindle speedwas 100,000 rpm and the insertion rate was 100 inches (254 cm) perminutes. For the 0.46 mm drill, the spindle speed was 80,000 rpms andthe insertion rate was 80 inches (203 cm) per minute. A retraction rateof 2.54 m (1000 inches) per minute and a 1.65 mm (0.065 inch) upperdrill head limit was held constant for both tool diameters. As usedherein, “drill head limit” means the distance that the drill tip waswithdrawn above the upper surface of the laminate.

The drill tip percent wear was determined based on a 500 hole drillingpattern shown in FIG. 12 which included 391 holes drilled in a 0.635 cmby 10.16 cm (0.25 inch by 4 inch) block (section 1280), followed by 100holes in a 10 by 10 hole pattern (section 1282), followed by 9 holes ina 3 by 3 hole pattern (section 1284). The holes in each section weredrilled at a hole density of 62 holes per square centimeter (400 holeper square inch). The pattern was repeated three additional times for atotal of 2000 holes. The drilling for Tests 1 and 2 was done using aUniline 2000 single head drilling machine and the drilling for Test 3was done using a CNC-7 single head drilling machine. Both machines areavailable from Esterline Technologies, Bellevue, Washington.

Table 13B shows the drill tip percent wear of the drill for Control GGand Sample HH for the 0.35 and 0.46 mm diameter drills after drilling2000 holes in the pattern discussed above. Each test was started with anew drill bit.

TABLE 13B Control GG Sample HH Test 1 Number of tools 3 3 0.35 mm dia.drill Average drill tip 28.8 22.2 percent wear Test 2 Number of tools 2020 0.46 mm dia. drill Average drill tip 34.0 24.4 percent wear Test 3Number of tools 10 10 0.46 mm dia. drill Average drill tip 30.8 29.3percent wear

As can be seen in Table 13B, Sample HH in Tests 1 and 2, which includesglass fiber filaments coated with a sizing as taught herein that iscompatible with laminate matrix resins, exhibited significantly lessdrill tip percent wear after 2000 holes than Control GG, which includesglass fiber filaments that had to be heat cleaned prior to being coatedwith a silane containing finishing sizing. Test 3 showed only a marginalimprovement in drill tip percent wear but it is believed that this isdue to the fact that the CNC-7 drilling machine used in this test wasolder and afforded less control during the drilling test than theUniline 2000 drilling machine used for Tests 1 and 2.

Locational Accuracy

A common metric used to assess the drilling performance of a laminate ishole locational accuracy. This test measures the deviation in thedistance of the actual hole location from its intended location. Themeasurement was taken on lower surface of the bottom laminate of a 3laminate stack where the drill exited the laminate stack, since it isexpected that this hole location would have the largest discrepancy fromthe intended or “true” hole location. This difference was assessed interms of the “deviation distance”, i.e., the distance from the actualtrue center of the drilled hole on the surface of the laminate to theintended true center of the hole. The deviation distance was measuredafter the 500 hole sequence discussed above was repeated 4 times, i.e.,after each tool drilled a total of 2000 holes. The deviation distancewas measured for the last drilled 100 hole pattern, i.e., the lastdrilled section 582. The holes were drilled using a 0.46 mm (0.018 inch)diameter series 508 drill from Tulon Co. of the type discussed above. Aswas used in the tool wear test, the spindle speed for the drill was80,000 rpms and the insertion rate was 80 inches per minute for a chipload of 0.001. The test was repeated eight times for each Control GG andSample HH with each test starting with a new drill.

Table 13C shows the result of the locational accuracy test for ControlGG and Sample HH after drilling 2000 holes.

TABLE 13C Control GG Sample HH number of drills 8 8 average deviationdistance (micrometer) 38 28

As can be seen, Sample HH exhibited a lower deviation distance thanControl GG, which is of particular significance when the laminate isused as an electronic support incorporating a large number of holes andcircuits. This is consistent with the drill tip percent wear data shownin Table 13B above. More specifically, it would be expected thatlaminates that exhibit less drill tip percent wear would also exhibitless deviation distance because the drill tips would be sharper for alonger number of drillings.

EXAMPLE 14

In Example 14, additional drill tool percent wear tests were conducted.Electrical grade laminates Control JJ and Samples AA, BB and KKincorporating a 7628 style fabric as discussed earlier were tested fordrill tool percent wear. The fabric in Control JJ was 7628-718 fabricfrom Clark-Schwebel, Inc. The fabrics in Samples AA, BB and KK werewoven from fill yarn comprising glass fibers coated with a resincompatible sizing as taught in Table 9A of Example 9 and Table 14Abelow, respectively, and warp yarn having glass fibers coated with adifferent polymeric matrix material compatible coating compositions¹⁸⁸.

¹⁸⁸ The warp yarn was PPG Industries, Inc.'s commercially availablefiber glass yarn product designated as G-75 glass fiber yarn coated withPPG Industries, Inc.'s 1383 binder.

TABLE 14A Weight Percent of Components on Total Solids Basis for Sizingused in Sample KK WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASISSAMPLE COMPONENT KK PVP K-30¹⁸⁹ 13.4 A-187¹⁹⁰ 1.9 A-174¹⁹¹ 3.8 EMERY6717¹⁹² 1.9 SAG 10¹⁹³ 0.2 RELEASECOAT-CONC 25¹⁹⁴ 3.8 POLARTHERM PT¹⁹⁵5.9 RD-847A¹⁹⁶ 23.0 DESMOPHEN 2000¹⁹⁷ 31.0 PLURONIC F-108¹⁹⁸ 8.4ALKAMULS EL-719¹⁹⁹ 2.5 ICONOL NP-6²⁰⁰ 4.2 LOI (%) 0.35 ¹⁸⁹PVP K-30polyvinyl pyrrolidone, which is commercially available from ISPChemicals of Wayne, New Jersey. ¹⁹⁰A-187gamma-glycidoxypropyltrimethoxysilane, which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹⁹¹A-174gamma-methacryloxypropyltrimethoxysilane, which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York. ¹⁹²EMERY ®6717 partially amidated polyethylene imine which is commerciallyavailable from Cognis Corporation of Cincinnati, Ohio. ¹⁹³SAG 10anti-foaming material, which is commercially available from CK WitcoCorporation of Greenwich, Connecticut. ¹⁹⁴ORPAC BORON NITRIDERELEASECOAT-CONC 25 boron nitride dispersion which is commerciallyavailable from ZYP Coatings, Inc. of Oak Ridge, Tennessee.¹⁹⁵POLARTHERM ® PT 160 boron nitride powder which is commerciallyavailable from Advanced Ceramics Corporation of Lakewood, Ohio.¹⁹⁶RD-847A polyester resin, which is commercially available from BordenChemicals of Columbus, Ohio. ¹⁹⁷DESMOPHEN 2000 polyethylene adipate diolwhich is commercially available from Bayer Corp. of Pittsburgh,Pennsylvania. ¹⁹⁸PLURONIC ™ F-108 polyoxypropylene-polyoxyethylenecopolymer which is commercially available from BASF Corporation ofParsippany, New Jersey. ¹⁹⁹ALKAMULS EL-719 polyoxyethylated vegetableoil which is commercially available from Rhone-Poulenc. ²⁰⁰ICONOL NP-6alkoxylated nonyl phenol which is commercially available from BASFCorporation of Parsippany, New Jersey.

The fabrics were subsequently formed into prepregs with an FR-4 epoxyresin having a Tg of 140° C. (designated 4000-2 resin by NelcoInternational Corporation of Anaheim, Calif.). The sizing compositionswere not removed from the fabric prior to prepregging. Laminates weremade by stacking 8-plies of the prepreg material and four layers of 1ounce copper (as shown below) and laminating them together at atemperature of 355° F. (about 179° C.), pressure of 300 pounds persquare inch (about 2.1 megaPascals) for 150 minutes (total cycle time).The thickness of the laminates with copper ranged from 0.052 inches(about 0.132 cm) to 0.065 inches (about 0.165 cm). In forming thelaminates, eight prepregs were stacked with copper layers in thefollowing arrangement:

-   -   one 1 oz/ft² shiny copper layer three prepreg layers    -   one 1 oz/ft² RTF (reverse treated foil) copper layer two prepreg        layers    -   one 1 oz/ft² RTF copper layer three prepreg layers    -   one 1 oz/ft² shiny copper layer        The finished laminates were trimmed to 40.6 cm by 50.8 cm (16        inches by 20 inches).

The drilling was conducted using a Uniline 2000 single head drillingmachine.

The drilling was performed on 3-high stacks of laminates (discussedabove) with a 0.010 inch (0.254 mm) thick aluminum entry and 0.1 inch(2.54 mm) thick aluminum clad particle board back-up. The drill toolpercent wear was determined for a 0.34 mm (0.0135 inches) tooldiameters, series 80 tungsten carbide drill available from Tulon Co.,Gardenia, Calif. The chip load during drilling was held constant at0.001, with a spindle speed of 95,000 rpm and insertion rate of 95inches (241 cm) per minutes. The drill retraction rate was 90 inches(2.29 m) per minute and the upper drill head limit was 0.059 inches (1.5mm) upper drill head limit.

The drill tip percent wear was examined based on a 1500 and 2500 holedrilling pattern. The holes in each section were drilled at a holedensity of 28 holes per square centimeter (about 178 hole per squareinch).

Table 14B shows the drill tip percent wear of the Control JJ and SamplesAA, BB and KK after drilling 1500 and 2500 holes. Each set of holes wasstarted with a new drill bit and each stack of laminates had ten 1500hole groupings and ten 2500 hole groupings. Three stacks of laminates ofeach fabric type were drilled so that the drill tip percent wear for 30drills were measured for each sample.

TABLE 14B Drill Tip Percent Wear Sample AA Sample BB Sample KK ControlJJ 1500 holes 21.5 19.5 19.8 24.9 2500 holes 28.0 24.3 25.3 28.3

As can be seen in Table 14B, Samples AA, BB and KK, which includes glassfiber filaments coated with a sizing as taught herein that is compatiblewith laminate matrix resins, exhibited significantly less percent wearafter 1500 holes than Control JJ, which includes glass fiber filamentsthat had to be heat cleaned prior to being coated with a silanecontaining finishing sizing. After 2500 holes, the amount of drill toolpercent wear for Samples AA, BB and KK is still less than for Control JJbut less pronounced. This is to be expected since the majority of thetool wear will occur during the earlier drilled holes rather than thelast holes drilled in a grouping.

Based on the above, although not limiting in the present invention, itis preferred that prepregs made with glass fiber fabric coated with apolymeric matrix compatible sizing as taught herein have a drilling tippercent wear of no greater than 32 percent, more preferably no greaterthan 30 percent, and most preferably no greater than 25 percent, asdetermined after drilling 2000 holes through a stack of 3 laminates,each laminate including eight prepregs, at a hole density of 400 holesper square inch and a chip load of 0.001 with a 0.46 mm (about 0.018inch) diameter tungsten carbide drill.

In addition, based in the above, although not limiting in the presentinvention, it is preferred that prepregs made with glass fiber fabriccoated with a polymeric matrix compatible sizing as taught herein have adeviation distance of no greater than 36 micrometers, more preferablynot greater than 33 micrometers, and most preferably not greater than 31micrometers, as determined after drilling 2000 holes through a stack of3 laminates, each laminate including eight prepregs, at a hole densityof 400 holes per square inch and a chip load of 0.001 with a 0.46 mm(about 0.018 inch) diameter tungsten carbide drill.

Although not meaning to be bound by any particular theory, it isbelieved that the presence of a solid lubricant in the glass fibercoating composition disclosed herein, and in one particular embodiment,the presence of the boron nitride, contributes to the improved drillingproperties of the laminates of the present invention. More particularly,the solid lubricant contributes to the reduction in drill wear andimprovement in locational accuracy of the drilled holes.

Improved drilling properties in laminate made with glass fibers coatedwith a resin compatible sizing as taught herein provides severaladvantages. First, longer drill life means that each drill bit can drillmore holes before resharpening or disposal. In addition, because thelocational accuracy of the holes drilled through the laminates of thepresent invention is greater than that for conventional laminates, it isexpected that more than three laminates can be stacked for drilling at asingle time with the same accuracy as that achieved in a 3 laminatestack of conventional laminates. Both of these advantages result is amore cost effective drilling operation. Furthermore, the locationalaccuracy of the holes drilled in the laminates is improved so that thequality of the electronic support incorporating the laminate inimproved.

EXAMPLE 15

The following samples in Table 15 represent additional embodiments ofthe invention. Coating sample LL was produced but not tested. Coatingsamples MM-QQ have not been produced.

TABLE 15 WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS SAMPLESCOMPONENTS LL MM NN OO PP QQ POLYOX WSR 301²⁰¹ 0.56 0.55 0.61 0.43 0.470.34 A-174²⁰² 3.68 4.31 4.74 3.32 3.68 2.61 A-187²⁰³ 1.74 2.08 2.29 1.601.78 1.26 DYNAKOLL Si 100²⁰⁴ 26.60 26.58 — 20.46 — 16.08 SERMUL EN668²⁰⁵ 3.33 — — — — — DESMOPHEN 2000²⁰⁶ 40.58 39.93 43.92 30.75 34.1424.15 SYNPERONIC F-108²⁰⁷ 9.98 — — — — — POLARTHERM PT 160²⁰⁸ 5.46 5.45— — 6.00 6.00 EUREDUR 140²⁰⁹ 4.43 — — — — — PLURONIC F-108²¹⁰ — 9.8310.81 7.56 8.40 5.94 MACOL NP-6²¹¹ — 3.28 3.60 2.52 2.80 1.98 VERSAMID140²¹² — 4.36 4.80 3.36 3.73 2.64 RELEASECOAT-CONC 3.64 3.63 — — 4.004.00 25²¹³ ROPAQUE OP-96²¹⁴ — — 29.23 30.00 35.00 35.00 est. % solids incoating 5.4 5.6 5.1 7.3 6.5 9.3 ²⁰¹POLYOX WSR 301 poly(ethylene oxide)which is commercially available from Union Carbide Corp. of Danbury,Connecticut. ²⁰²A-174 gamma-methacryloxypropyltrimethoxysilane which iscommercially available from CK Witco Corp. of Tarrytown, New York.²⁰³A-187 gamma-glycidoxy-propyltrimethoxysilane which is commerciallyavailable from CK Witco Corp. of Tarrytown, New York. ²⁰⁴DYNAKOLL Si 100rosin which is commercially available from Eka Chemicals AB, Sweden.²⁰⁵SERMUL EN 668 ethoxylated nonylphenol which is commercially availablefrom CON BEA, Benelux. ²⁰⁶DESMOPHEN 2000 polyester polyol which iscommercially available from Bayer. Corp. of Pittsburgh, Pennsylvania.²⁰⁷SYNPERONIC F-108 polyoxypropylene-polyoxyethylene copolymer; it isthe European counterpart to PLURONIC F-108. ²⁰⁸POLARTHERM PT 160 boronnitride powder which is commercially available from Advanced CeramicsCorporation of Lakewood, Ohio. ²⁰⁹EUREDUR 140 is a polyamide resin,which is commercially available from Ciba Geigy, Belgium. ²¹⁰PLURONICF-108 polyoxypropylene-polyoxyethylene copolymer which is commerciallyavailable from BASF Corporation of Parsippany, New Jersey. ²¹¹MACOL NP-6nonylphenol surfactant which is commercially available from BASF ofParsippany, New Jersey. ²¹²VERSAMID 140 polyamide resin which iscommercially available from Cognis Corp. of Cincinnati, Ohio. ²¹³ORPACBORON NITRIDE RELEASECOAT-CONC 25 boron nitride dispersion which iscommercially available from ZYP Coatings, Inc. of Oak Ridge, Tennessee.²¹⁴ROPAQUE OP-96, 0.55 micron particle dispersion which is commerciallyavailable from Rohm and Haas Company of Philadelphia, Pennsylvania.

EXAMPLE 16

Unclad laminates were made from the materials and by the processes asdescribed in Example 9, except that no copper was used duringlamination. Each of the unclad laminates were then cut into 52, 1 inch×½inch (about 2.54 centimeter×about 1.27 centimeter) rectangular pieces.About half of the pieces were cut parallel to the warp direction andabout half of the piece were cut parallel to the fill direction, 26rectangular pieces from each laminate (13 cut parallel to the warpdirection and 13 cut parallel to the fill direction) were then placed inreflux apparatus with water and the water was brought to a boil. Thewater was allowed to boil for 24 hours. After 24 hours, the piece wereremoved from the water and towel dried. The remaining 26 piece from eachlaminate were not boiled. An unclad control laminate made using aconventional heat-cleaned and finished fabric in the same manner asdescribed above in Example 9 for making the test laminates, was alsofabricated and tested according to the above procedure.

The short beam shear strength of both the boiled and unboiled piece werethen measured according to ASTM D 2344-84. The result of the testing aregiven below in Table 9, where Unclad Samples M, BB and CC correspond tolaminates made using fabrics (described in Example 9) having fiberssized with sizing compositions M, BB, CC, respectively. As discussedabove, the control sample was made using a conventional heat-cleaned andfinished fabric. The thickness of the test laminates (Unclad Samples AA,BB and CC) ranged from 0.050 inches (about 0.127 centimeters) to 0.063inches (about 0.160 centimeters). The ratio of the span length to samplethickness during testing was 5.

TABLE 16 Test Units AA BB CC Control Short Beam Pounds per 7787 84777769 7382 Shear Strength, square inch   (54)   (56)   (54)   (51) NoBoil, Warp Direction (megaPascals) Sample Thickness N = 13 Inches  0.060   0.050   0.056   0.055 (centimeters)   (0.152)   (0.127)  (0.142)   (0.140) Short Beam Pounds per 6626 7594 7118 5506 ShearStrength, square inch   (46)   (52)   (49)   (38) No Boil, FillDirection (megaPascals) Sample Thickness N = 13 Inches   0.061   0.050  0.060   0.055 (centimeters)   (0.155)   (0.127)   (0.152)   (0.140)Short Beam Pounds per 5695 6522 5081 4929 Shear Strength, square inch  (39)   (45)   (35)   (34) 24 Hour Boil, Warp Direction (megaPascals)Sample Thickness N = 13 Inches   0.061   0.051   0.057   0.057(centimeters)   (0.155)   (0.130)   (0.145)   (0.145) Short Beam Poundsper 5266 5832 5179 4116 Shear Strength, square inch   (36)   (40)   (36)  (28) 24 Hour Boil, Fill Direction (megaPascals) Sample Thickness N =13 Inches   0.063   0.051   0.062   0.056 (centimeters)   (0.160)  (0.130)   (0.157)   (0.142)

The short beam shear strengths of the test laminates (Unclad Samples M,BB, CC) in both the warp and fill directions, both before and afterwater boil, were observed to be higher than the control sample in thistesting.

EXAMPLE 17

Fill yarns made from E-glass fiber strands sized with sizing compositionCC given in Table 9A of Example 9 and warp yarns made PPG Industries,Inc.'s 1383 commercially available fiber glass yarn product were woveninto 7628 style fabric using an air-jet loom. The fabric wassubsequently prepregged and laminated to form copper clad laminates asdescribed above in Example 9.

Copper clad laminate CC (as described above in Example 9) wassubsequently processed (i.e., drilled, plated and patterned) into testboards having a plurality of least patterns for testing metal migrationperformance. More particularly, each board included three sets of sevensimilar circuit patterns 1310 as shown in FIG. 13. One set of patternswas oriented along the X-axis of the board, another along the Y-axis ofthe board, and a third along a 45° angle across the board. Each circuitpattern 1310 included 50 rows of five drilled holes 1312, each having adiameter of 13.5 mil., and a center-to-center spacing between holes Inadjacent rows ranging from 40 to 54.7 mil. In drilling these holes, twoboards were stacked together so that both could be drilled in a singledrilling operation. Alternating rows of holes in each pattern wereinterconnected by bus bar 1314 and leads 1316 along a first majorsurface of the board as shown in FIG. 13. Wire leads were soldered toeach bus bar for connection to a power source. Each circuit furtherincluded a 1 K ohm surface resistor 1322 to ensure that if one circuitfailed, power supply to the remaining circuits would be maintained. Eachboard was soaked In 76.7° C. (170° F.) deionized water for ten minutesto remove any solder flux residue and dried. The boards were then placedin a chamber at 85° C. (185° F.) and 85% relative humidity, and a 13.5volt DC current was continuously applied across the patterns. Every. 200hours the chamber was shut down, the chamber door was opened to allowthe patterns to stabilize to ambient lab temperature, and the insulationresistance for each pattern was measured.

There were two Sample CC boards and two control boards. The controlboards were made in the same way as the Sample CC boards but usedconventional heat-cleaned and finished fabrics. Each board included 21circuit patterns (i.e., three sets of seven circuit patterns) for atotal of 42 circuits tested for both the Sample CC boards and thecontrol boards. The results for 200, 400 and 1000 hours are given belowin Table 17 where the tabled values are the number of patterns with thespecified resistance.

TABLE 17 Insulation Resistance Sample CC Control OHMS 200 Hrs. 400 Hrs.1000 Hrs. 400 Hrs. Short 0 1 7 42   10⁵ 1 4 2 0   10⁶ 1 1 1 0   10⁷ 0 20 0   10⁸ 1 0 1 0   10⁹ 3 2 1 0 ≧10¹⁰ 36 32 30 0

The Sample CC boards had fewer shorts than the control boards after 200hours of exposure. After 400 hours of exposure, all the control boardpatterns had failed. For purposes of this test sample, a “short” refersto an insulation resistance value of less than 105 ohms.

EXAMPLE 18

Each of the components in the amount set forth in Table 18A were mixedto form aqueous resin compatible primary size Sample RR according to thepresent invention. Less than 1 weight percent of acetic acid on a totalweight basis was included in the composition. Sample RR was applied toglass fibers forming G-75 E-glass fiber strands. The coated glass fiberstrands were twisted to form a twisted yarn and wound onto bobbins in asimilar manner using conventional twisting equipment. The coated yarnhad an LOI of 0.35%.

TABLE 18A Weight Percent of Component on Total Solids Basis for SampleRR Sizing COMPONENT SAMPLE RR RD-847A²¹⁵ 27.0 DESMOPHEN 2000²¹⁶ 36.2 PVPK-30²¹⁷ 9.0 A-187²¹⁸ 2.1 A-174²¹⁹ 4.4 PLURONIC F-108²²⁰ 9.0 VERSAMID140²²¹ 4.4 MACOL NP-6²²² 5.4 POLARTHERM PT 160²²³ 0.9 RELEASECOAT-CONC25²²⁴ 1.5 acetic acid <0.1 ²¹⁵RD-847A polyester resin, which iscommercially available from Borden Chemicals of Columbus, Ohio.²¹⁶DESMOPHEN 2000 polyethylene adipate diol, which is commerciallyavailable from Bayer of Pittsburgh, Pennsylvania. ²¹⁷PVP K-30 polyvinylpyrrolidone, which is commercially available from ISP Chemicals ofWayne, New Jersey. ²¹⁸A-187 gamma-glycidoxypropyltrimethoxysilane, whichis commercially available from OSi Specialties, Inc. of Tarrytown, NewYork. ²¹⁹A-174 gamma-methacryloxypropyltrimethoxysilane, which iscommercially available from OSi Specialties, Inc. of Tarrytown, NewYork. ²²⁰PLURONIC ™ F-108 polyoxypropylene-polyoxyethylene copolymer,which is commercially available from BASF Corporation of Parsippany, NewJersey. ²²¹VERSAMID 140 polyamide, which is commercially available fromGeneral Mills Chemicals, Inc. ²²²MACOL NP-6 nonylphenol surfactant,which is commercially available from BASF of Parsippany, New Jersey.²²³POLARTHERM ® PT 160 boron nitride powder particles, which arecommercially available from Advanced Ceramics Corporation of Lakewood,Ohio. ²²⁴ORPAC BORON NITRIDE RELEASECOAT-CONC 25, which is commerciallyavailable from ZYP Coatings, Inc. of Oak Ridge, Tennessee.

Each of the components in the amount set forth in Table 18B was mixed toform aqueous resin compatible primary size Sample SS according to thepresent invention. Sample SS was applied to glass fibers forming G-75E-glass fiber strands and the strands were not twisted. The coated,untwisted yarn had an LOI of 0.7%.

TABLE 18B Pounds of Component per 100 Gallons of Sample SS SizingCOMPONENT SAMPLE SS MAPEG 600 DOT²²⁵ 9.24 ALUBRASPIN 226²²⁶ 1.9 A-174²²⁷10.9 A-187²²⁸ 5.45 A-1100²²⁹ 2.41 EPON 880²³⁰ 91.1 PLURONIC F-108²³¹9.11 ALKAMULS EL-719²³² 9.11 MACOL OP-10-SP²³³ 4.57 EPIREZ 3522²³⁴ 20.9acetic acid 2.6 ²²⁵is an ethyoxylated di-tallate from BASF Corp.²²⁶ALUBRASPIN 226 partially amidated polyethylene imine, which iscommercially available from BASF Corp. of Parsippany, New Jersey.²²⁷A-174 gamma-methacryloxypropyltrimethoxysilane which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York. ²²⁸A-187gamma-glycidoxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ²²⁹A-1100amino-functional organo silane coupling agent which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York. ²³⁰EPON ®880 epoxy resin, which is commercially available from Shell ChemicalCompany of Houston, Texas. ²³¹PLURONIC ™ F-108polyoxypropylene-polyoxyethylene copolymer which is commerciallyavailable from BASF Corporation of Parsippany, New Jersey. ²³²ALKAMULSEL-719 polyoxyethylated vegetable oil which is commercially availablefrom Rhone-Poulenc. ²³³MACOL OP-10 SP ethoxylated alkylphenol which iscommercially available from BASF Corp. of Parsippany, New Jersey.²³⁴Dispersion of a solid bis-phenol A glycidyl ether epoxy resin fromShell Chemical Company of Houston, Texas.

Yarns sized with Samples RR and SS were used as warp and fill (or weft)yarns and woven into 7628 style fabric. A control yarn, which was acommercially available G-75 E-glass twisted yarn having fibers coatedwith PPG 695 sizing and available from PPG Industries, Inc., Pittsburgh,Pa. (hereinafter the “Control Sample”), was also woven into a 7628 stylefabric. The sized warp and fill control yarns had an LOI of 1%. Prior toweaving, the warp yarn was slashed with a polyvinyl alcohol compositionthat increased the LOI of the warp yarn to about 2 to about 2.5%. Theresulting fabric had an LOI ranging from 1.6 to 1.9%.

Each fabric was tested for air permeability according the testprocedures established in ASTM D 737 Standard Test Method for AirPermeability of Textile Fabrics. The average air permeability for thefabric wovens is shown below in Table 18C.

TABLE 18C Air Permeability (standard cubic feet per minute per squarefoot) Control Sample 41 Sample RR 2.8 Sample SS 1.6As can be seen in Table 18C, the air permeability for the woven fabricsincorporating Samples A and B is significantly lower than that of thefabric woven with the Control Sample.

EXAMPLE 19

Table 19 includes additional nonlimiting sizing formulations applied toglass fibers that were subsequently woven into a fabric. Less than 1weight percent of acetic acid was included in each composition.

TABLE 19 Weight Percent of Component on a Total Solids Basis COMPONENTSample TT Sample UU Sample VV Sample WW Sample XX PVP K-30²³⁵ 13.7 13.515.3 14.7 14.2 STEPANTEX 653²³⁶ 27.9 13.6 12.6 A-187²³⁷ 1.7 1.9 1.9 1.81.7 A-174²³⁸ 3.4 3.8 3.8 3.7 3.5 EMERY 6717²³⁹ 2.3 1.9 2.5 2.4 2.4 MACOLOP-10²⁴⁰ 1.5 1.7 1.6 1.6 TMAZ-81²⁴¹ 3.0 3.4 3.3 3.1 MAZU DF-136²⁴² 0.20.3 0.2 0.2 ROPAQUE OP-96²⁴³ 39.3 43.9 42.3 40.7 RELEASECOAT-CONC 25²⁴⁴4.2 6.4 4.5 POLARTHERM PT 160²⁴⁵ 2.7 2.6 2.8 SAG 10²⁴⁶ 0.2 RD-847A²⁴⁷23.2 DESMOPHEN 2000²⁴⁸ 31.2 PLURONIC F-108²⁴⁹ 8.5 ALKAMULS EL-719²⁵⁰ 3.4ICONOL NP-6²⁵¹ 3.4 FLEXOL EPO²⁵² 13.6 30.0 12.6 ²³⁵PVP K-30 polyvinylpyrrolidone which is commercially available from ISP Chemicals of Wayne,New Jersey. ²³⁶STEPANTEX 653 which is commercially available from StepanCompany of Maywood, New Jersey. ²³⁷A-187gamma-glycidoxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ²³⁸A-174gamma-methacryloxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ²³⁹EMERY ® 6717partially amidated polyethylene imine which is commercially availablefrom Cognis Corporation of Cincinnati, Ohio. ²⁴⁰MACOL OP-10 ethoxylatedalkylphenol; this material is similar to MACOL OP-10 SP except thatOP-10 SP receives a post treatment to remove the catalyst; MACOL OP-10is no longer commercially available. ²⁴¹TMAZ-81 ethylene oxidederivative of a sorbitol ester which is commercially available from BASFCorp. of Parsippany, New Jersey. ²⁴²MAZU DF-136 anti-foaming agent whichis commercially available from BASF Corp. of Parsippany, New Jersey.²⁴³ROPAQUE ® OP-96, 0.55 micron particle dispersion which iscommercially available from Rohm and Haas Company of Philadelphia,Pennsylvania. ²⁴⁴ORPAC BORON NITRIDE RELEASECOAT-CONC 25 boron nitridedispersion which is commercially available from ZYP Coatings, Inc. ofOak Ridge, Tennessee. ²⁴⁵POLARTHERM ® PT 160 boron nitride powder whichis commercially available from Advanced Ceramics Corporation ofLakewood, Ohio. ²⁴⁶SAG 10 anti-foaming material, which is commerciallyavailable from CK Witco Corporation of Greenwich, Connecticut.²⁴⁷RD-847A polyester resin which is commercially available from BordenChemicals of Columbus, Ohio. ²⁴⁸DESMOPHEN 2000 polyethylene adipate diolwhich is commercially available from Bayer Corp. of Pittsburgh,Pennsylvania. ²⁴⁹PLURONIC ™ F-108 polyoxypropylene-polyoxyethylenecopolymer which is commercially available from BASF Corporation ofParsippany, New Jersey. ²⁵⁰ALKAMULS EL-719 polyoxyethylated vegetableoil which is commercially available from Rhone-Poulenc. ²⁵¹ICONOL NP-6alkoxylated nonyl phenol which is commercially available from BASFCorporation of Parsippany, New Jersey. ²⁵²FLEXOL EPO epoxidized soybeanoil commercially available from Union Carbide Corp. of Danbury,Connecticut.

From the foregoing description, it can be seen that the presentinvention provides glass fiber strands having an abrasion-resistantcoating which provide good thermal stability, low corrosion andreactivity in the presence of high humidity, reactive acids and alkaliesand compatibility with a variety of polymeric matrix materials. Thesestrands can be twisted or chopped, formed into a roving, chopped mat orcontinuous strand mat or woven or knitted into a fabric for use in awide variety of applications, such-as reinforcements for composites suchas printed circuit boards.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications that are within the spirit and scopeof the invention, as defined by the appended claims.

1. An at least partially coated fiber strand comprising a plurality ofglass fibers having a powdered coating composition on at least a portionof at least one of the glass fibers, the powdered coating compositioncomprising at least one coating comprising greater than 20 weightpercent on a total solids basis of a plurality of particles selectedfrom inorganic particles, organic hollow particles, composite particles,and mixtures of any of the foregoing, wherein the plurality of particleshave a Mohs' hardness value which does not exceed the Mohs' hardnessvalue of the glass fibers.
 2. An at least partially coated fiber strandaccording to claim 1, wherein the coating composition is a resincompatible coating composition.
 3. An at least partially coated fiberstrand according to claim 1, wherein the plurality of particles have aMohs' hardness value ranging from 0.5 to
 6. 4. An at least partiallycoated fiber strand according to claim 1, wherein the plurality of glassfibers are selected from E-glass fibers, D-glass fibers, S-glass fibers,Q-glass fibers, E-glass derivative fibers, and mixtures of any of theforegoing.
 5. An at least partially coated fiber strand according toclaim 4, wherein the plurality of glass fibers are selected from E-glassfibers.
 6. An at least partially coated fiber strand according to claim4, wherein the plurality of glass fibers are selected from E-glassderivative fibers.
 7. An at least partially coated fiber strandaccording to claim 1, wherein the inorganic particles are selected fromboron nitride, graphite, molybdenum disulfide, talc, mica, kaolinite,gypsum, calcium carbonate, calcium fluoride, zinc oxide, aluminum,copper, iron, gold, nickel, palladium, platinum, silver, zinc sulfide,and mixtures of any of the foregoing.
 8. An at least partially coatedfiber strand according to claim 7, wherein the inorganic particlescomprise at least one particle selected from boron nitride particles. 9.An at least partially coated fiber strand according to claim 8, whereinthe inorganic particles comprise at least one particle selected fromhexagonal crystal structure boron nitride particles.
 10. An at leastpartially coated fiber strand according to claim 1, wherein the organichollow particles are selected from acrylic polymers.
 11. An at leastpartially coated fiber strand according to claim 10, wherein the acrylicpolymers are selected from copolymers formed from at least one styrenemonomer and at least one acrylic acid monomer, and polymers formed fromat least one methacrylate monomer.
 12. An at least partially coatedfiber strand according to claim 1, wherein the composite particles areselected from particles that have a hardness at their surface that isdifferent from the hardness of the internal portions of the particlebeneath its surface.
 13. An at least partially coated fiber strandaccording to claim 12, wherein the composite particles are selected fromparticles formed from a primary material that is coated, clad orencapsulated with at least one secondary material.
 14. An at leastpartially coated fiber strand according to claim 12, wherein thecomposite particles are selected from particles formed from a primarymaterial that is coated, clad or encapsulated with a differing form ofthe primary material.
 15. An at least partially coated fiber strandaccording to claim 1, wherein the composite particles are selected fromparticles formed from an inorganic material coated with a materialselected from silicas, carbonates and nanoclays.
 16. An at leastpartially coated fiber strand according to claim 1, wherein theplurality of particles are present in the coating composition in anamount ranging from 25 to 80 weight percent on a total solids basis. 17.An at least partially coated fiber strand according to claim 16, whereinthe plurality of particles are present in the coating composition in anamount ranging from 50 to 60 weight percent on a total solids basis. 18.An at least partially coated fiber strand according to claim 1, whereinthe coating composition further comprises at least one lubriciousmaterial different from said plurality of particles.
 19. An at leastpartially coated fiber strand according to claim 1, wherein the coatingcomposition further comprises at least one film-forming material.
 20. Anat least partially coated fiber strand according to claim 1, wherein thecoating composition comprises a primary coating of at least one sizingcomposition on at least a portion of a surface of at least one of theglass fibers and a secondary coating composition, on at least a portionof the primary coating, comprising the plurality of particles having aMohs' hardness value which does not exceed the Mohs' hardness value ofthe glass fibers.
 21. An at least partially coated fiber strandaccording to claim 1, wherein the coating composition comprises aprimary coating of at least one sizing composition on at least a portionof a surface of at least one of the glass fiber, a secondary coating onat least a portion of the primary coating, and a tertiary coatingcomposition, on at least a portion of the secondary coating, comprisingthe plurality of particles having a Mohs' hardness value which does notexceed the Mohs' hardness value of the glass fibers.
 22. An at leastpartially coated fiber strand according to claim 1, wherein the coatingcomposition comprises a resin reactive diluent.
 23. An at leastpartially coated fiber strand according to claim 22, wherein the resinreactive diluent is a lubricant comprising one or more functional groupscapable of reacting with an epoxy resin system and selected from thegroup consisting of amine groups, alcohol groups, anhydride groups, acidgroups and epoxy groups.
 24. An at least partially coated fiber strandaccording to claim 1, wherein the plurality of lamellar particles have athermal conductivity of at least 1 Watt per meter ° K at a temperatureof 300° K.
 25. An at least partially coated fiber strand according toclaim 24, wherein the plurality of lamellar particles have a thermalconductivity ranging from 5 to 2000 Watts per meter °K at a temperatureof 300° K.
 26. An at least partially coated fiber strand comprising aplurality of glass fibers having a powdered coating composition on atleast a portion of a surface of at least one of said glass fibers, thepowdered coating composition comprising: (a) a plurality of holloworganic particles having a Mohs' hardness value which does not exceedthe Mohs' hardness value of the glass fibers; and (b) at least onepolymeric material different from at least one of the hollow organicparticles.
 27. An at least partially coated fiber strand according toclaim 26, wherein the coating composition is a resin compatible coatingcomposition.
 28. An at least partially coated fiber strand according toclaim 26, wherein the plurality of particles have a Mohs' hardness valueranging from 0.5 to
 6. 29. An at least partially coated fiber strandaccording to claim 26, wherein the at least one polymeric material isselected from polymeric organic materials, polymeric inorganicmaterials, and mixtures thereof.
 30. A glass fiber comprising a powderedcoating composition comprising at least one coating comprising greaterthan 20 weight percent on a total solids basis of a plurality ofparticles selected from inorganic particles, organic hollow particles,and composite particles, wherein the plurality of particles have a Mohs'hardness value which does not exceed the Mohs' hardness value of theglass fiber.
 31. A fiber according to claim 30, wherein the coatingcomposition is a resin compatible coating composition.
 32. A fiberaccording to claim 30, wherein the plurality of particles have a Mohs'hardness value ranging from 0.5 to
 6. 33. A glass fiber comprising apowdered coating composition comprising: (a) a plurality of holloworganic particles having a Mohs' hardness value which does not exceedthe Mohs' hardness value of the glass fiber; and (b) at least onepolymeric material different from at least one of the hollow organicparticles.
 34. A fiber according to claim 33, wherein the coatingcomposition is a resin compatible coating composition.
 35. A fiberaccording to claim 33, wherein the plurality of particles have a Mohs'hardness value ranging from 0.5 to 6.